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Daily Challenge #179 - Hide Phone Numbers

thepracticaldev profile image dev.to staff ・1 min read

Daily Challenge (275 Part Series)

1) Daily Challenge #1 - String Peeler 2) Daily Challenge #2 - String Diamond 3 ... 273 3) Daily Challenge #3 - Vowel Counter 4) Daily Challenge #4 - Checkbook Balancing 5) Daily Challenge #5 - Ten Minute Walk 6) Daily Challenge #6 - Grandma and her friends 7) Daily Challenge #7 - Factorial Decomposition 8) Daily Challenge #8 - Scrabble Word Calculator 9) Daily Challenge #9 - What's Your Number? 10) Daily Challenge #10 - Calculator 11) Daily Challenge #11 - Cubic Numbers 12) Daily Challenge #12 - Next Larger Number 13) Daily Challenge #13 - Twice Linear 14) Daily Challenge #14 - Square into Squares 15) Daily Challenge #15 - Stop gninnipS My sdroW! 16) Daily Challenge #16 - Number of People on the Bus 17) Daily Challenge #17 - Double Trouble 18) Daily Challenge #18 - Triple Trouble 19) Daily Challenge #19 - Turn numbers into words 20) Daily Challenge Post #20 - Number Check 21) Daily Challenge #21 - Human Readable Time 22) Daily Challenge #22 - Simple Pig Latin 23) Daily Challenge #23 - Morse Code Decoder 24) Daily Challenge #24 - Shortest Step 25) Daily Challenge #25 - Double Cola 26) Daily Challenge #26 - Ranking Position 27) Daily Challenge #27 - Unlucky Days 28) Daily Challenge #28 - Kill the Monster! 29) Daily Challenge #29 - Xs and Os 30) Daily Challenge #30 - What is the price? 31) Daily Challenge #31 - Count IPv4 Addresses 32) Daily Challenge #32 - Hide Phone Numbers 33) Daily Challenge #33 - Did you mean...? 34) Daily Challenge #34 - WeIrD StRiNg CaSe 35) Daily Challenge #35 - Find the Outlier 36) Daily Challenge #36 - Let's go for a run! 37) Daily Challenge #37 - Name Swap 38) Daily Challenge #38 - Middle Name 39) Daily Challenge #39 - Virus 40) Daily Challenge #40 - Counting Sheep 41) Daily Challenge #41 - Greed is Good 42) Daily Challenge #42 - Caesar Cipher 43) Daily Challenge #43 - Boardgame Fight Resolver 44) Daily Challenge #44 - Mexican Wave 45) Daily Challenge #45 - Change Machine 46) Daily Challenge #46 - ??? 47) Daily Challenge #47 - Alphabets 48) Daily Challenge #48 - Facebook Likes 49) Daily Challenge #49 - Dollars and Cents 50) Daily Challenge #50 - Number Neighbor 51) Daily Challenge #51 - Valid Curly Braces 52) Daily Challenge #52 - Building a Pyramid 53) Daily Challenge #53 - Faro Shuffle 54) Daily Challenge #54 - What century is it? 55) Daily Challenge #55 - Building a Pile of Cubes 56) Daily Challenge #56 - Coffee Shop 57) Daily Challenge #57 - BMI Calculator 58) Daily Challenge #58 - Smelting Iron Ingots 59) Daily Challenge #59 - Snail Sort 60) Daily Challenge #60 - Find the Missing Letter 61) Daily Challenge #61 - Evolution Rate 62) Daily Challenge #62 - Josephus Survivor 63) Daily Challenge #63- Two Sum 64) Daily Challenge #64- Drying Potatoes 65) Daily Challenge #65- A Disguised Sequence 66) Daily Challenge #66- Friend List 67) Daily Challenge #67- Phone Directory 68) Daily Challenge #68 - Grade Book 69) Daily Challenge #69 - Going to the Cinema 70) Daily Challenge #70 - Pole Vault Competition Results 71) Daily Challenge #71 - See you next Happy Year 72) Daily Challenge #72 - Matrix Shift 73) Daily Challenge #73 - ATM Heist 74) Daily Challenge #74 - Free Pizza 75) Daily Challenge #75 - Set Alarm 76) Daily Challenge #76 - Bingo! (or not...) 77) Daily Challenge #77 - Bird Mountain 78) Daily Challenge #78 - Number of Proper Fractions with Denominator d 79) Daily Challenge #79 - Connect Four 80) Daily Challenge #80 - Longest Vowel Change 81) Daily Challenge #81 - Even or Odd 82) Daily Challenge #82 - English Beggars 83) Daily Challenge #83 - Deodorant Evaporator 84) Daily Challenge #84 - Third Angle of a Triangle 85) Daily Challenge #85 - Unwanted Dollars 86) Daily Challenge #86 - Wouldn't, not Would. 87) Daily Challenge #87 - Pony Express 88) Daily Challenge #88 - Recursive Ninjas 89) Daily Challenge #89 - Extract domain name from URL 90) Daily Challenge #90 - One Step at a Time 91) Daily Challenge #91 - Bananas 92) Daily Challenge #92 - Boggle Board 93) Daily Challenge #93 - Range Extraction 94) Daily Challenge #94 - Last Digit 95) Daily Challenge #95 - CamelCase Method 96) Daily Challenge #96 - Easter Egg Crush Test 97) Daily Challenge #97 - Greed is Good 98) Daily Challenge #98 - Make a Spiral 99) Daily Challenge #99 - Balance the Scales 100) Daily Challenge #100 - Round Up 101) Daily Challenge #101 - Parentheses Generator 102) Daily Challenge #102 - Pentabonacci 103) Daily Challenge #103 - Simple Symbols 104) Daily Challenge #104 - Matrixify 105) Daily Challenge #105 - High-Sum Matrix Drop 106) Daily Challenge #106 - Average Fuel Consumption 107) Daily Challenge #107 - Escape the Mines 108) Daily Challenge #108 - Find the Counterfeit Coin 109) Daily Challenge #109 - Decorate with Wallpaper 110) Daily Challenge #110 - Love VS. Friendship 111) Daily Challenge #111 - 99 Bottles of Beer 112) Daily Challenge #112 - Functions of Integers on the Cartesian Plane 113) Daily Challenge #113 - Iterative Rotation Cipher 114) Daily Challenge #114 - Speed Control 115) Daily Challenge #115 - Look and Say Sequence 116) Daily Challenge #116 - Shortest Knight Path 117) Daily Challenge #117 - MinMinMax 118) Daily Challenge #118 - Reversing a Process 119) Daily Challenge #119 - Adding Big Numbers 120) Daily Challenge #120 - Growth of a Population 121) Daily Challenge #121 - Who has the most money? 122) Daily Challenge #122 - Clockwise Spirals 123) Daily Challenge #123 - Curry me Softly 124) Daily Challenge #124 - Middle Me 125) Daily Challenge #125 - 23 Matches or More 126) Daily Challenge #126 - The Supermarket Line 127) Daily Challenge #127 - Playing with Passphrases 128) Daily Challenge #128 - Blackjack Scorer 129) Daily Challenge #129 - Clay Pigeon Shooting 130) Daily Challenge #130 - GCD Sum 131) Daily Challenge #131 - Remove Anchor from URL 132) Daily Challenge #132 - Is my friend cheating? 133) Daily Challenge #133 - Suitcase Packing 134) Daily Challenge #134 - Rice and Chessboard Problem 135) Daily Challenge #135 - The Wide Mouthed Frog! 136) Daily Challenge #136 - The Deaf Rats of Hamelin 137) Daily Challenge #137 - Help the Bookseller 138) Daily Challenge #138 - Do I get a Bonus? 139) Daily Challenge #138 - Keep Up the Hoop 140) Daily Challenge #140 - I love you, a little, a lot, passionately ... not at all 141) Daily Challenge #141 - Two Sum 142) Daily Challenge #142 - Parts of a Whole 143) Daily Challenge #143 - Big Arithmetic 144) Daily Challenge #144 - Box Office Clerk 145) Daily Challenge #145 - SET Card Game 146) Daily Challenge #146 - The Dollar Game 147) Daily Challenge #147 - NIM 148) Daily Challenge #148 - Disemvowel Trolls 149) Daily Challenge #149 - Fun with Lamps 150) Daily Challenge #150 - Boggle Guess Validator 151) Daily Challenge #151 - Reverse Parentheses 152) Daily Challenge #152 - Strongest Number in an Interval 153) Daily Challenge #153 - Horse Race Gamble 154) Daily Challenge #154 - Stable Arrangement 155) Daily Challenge #155 - Royal Arranged Marriages 156) Daily Challenge #162 - Taxi Dispatching 157) Daily Challenge #163 - Significant Figures 158) Daily Challenge #164 - Jump 159) Daily Challenge #165 - Password Lost in a Grid 160) Daily Challenge #166 - Cat and Mouse 161) Daily Challenge #167 - Return String As Sorted Blocks 162) Daily Challenge #168 - [Code golf] f (f (f b)) = f b 163) Daily Challenge #169 - Christmas Tree 164) Daily Challenge #170 - Pokemon Damage Calculator 165) Daily Challenge #171 - Ordering Beers in Poland 166) Daily Challenge #172 - Find All in an Array 167) Daily Challenge #173 - Pandemia 168) Daily Challenge #174 - Soccer League Table 169) Daily Challenge #175 - Complementary DNA 170) Daily Challenge #176 - Loopover 171) Daily Challenge #177 - Supersize Me 172) Daily Challenge #178 - Create Phone Numbers 173) Daily Challenge #179 - Hide Phone Numbers 174) Daily Challenge #180 - SMS Shortener 175) Daily Challenge #181 - Is King in Check? 176) Daily Challenge #182 - Arrh, grabscrab! 177) Daily Challenge #183 - Automorphic Numbers 178) Daily Challenge #184 - Form the Minimum 179) Daily Challenge #185 - House Numbers Sum 180) Daily Challenge #186 - Jumping Frog 181) Daily Challenge #187 - Most Sales 182) Daily Challenge #188 - Break camelCase 183) Daily Challenge #189 - Convert Number into Reversed Array 184) Daily Challenge #190 - capitalizeFirstLast 185) Daily Challenge #191 - Alphabetical Addition 186) Daily Challenge #192 - Can you Survive the Zombies? 187) Daily Challenge #193 - What's the Real Floor? 188) Daily Challenge #194 - Spread Number 189) Daily Challenge #195 - No Zeroes for Heroes 190) Daily Challenge #196 - Flou 191) Daily Challenge #197 - Population Growth 192) Daily Challenge #198 - 21 Blackjack 193) Daily Challenge #199 - List of All Rationals 194) Daily Challenge #200 - Longest Linear Palindromic Substring 195) Daily Challenge #201 - Complete the Pattern 196) Daily Challenge #202 - Complete the Pattern II 197) Daily Challenge #203 - Pascal's Triangle 198) Daily Challenge #204 - Partial Keys 199) Daily Challenge #205 - Consonant String Value 200) Daily Challenge #206 - Pound Means Backspace 201) Daily Challenge #207 - Snakes and Ladders 202) Daily Challenge #208 - Delete Occurrences of an Element 203) Daily Challenge #209 - Roman Numerals 204) Daily Challenge #210 - Separate Capitalization 205) Daily Challenge #211 - Product Partitions 206) Daily Challenge #212 - DNA to RNA 207) Daily Challenge #213 - Are they the "same"? 208) Daily Challenge #214 - Persistent Bugger 209) Daily Challenge #215 - Difference of 2 210) Daily Challenge #216 - Rainfall 211) Daily Challenge #217 - SMS w/ an Old Phone 212) Daily Challenge #218 - Possible Sides of a Non-Right Triangle 213) Daily Challenge #219 - Compare Strings 214) Daily Challenge #220 - What Dominates Your Array? 215) Daily Challenge #221 - The Merchant of York 216) Daily Challenge #222 - Parse Bank Account Numbers 217) Daily Challenge #223 - Responsible Drinking 218) Daily Challenge #224 - Password Validator 219) Daily Challenge #225 - Square'n'Sum 220) Daily Challenge #226 - Array to HTML Table 221) Daily Challenge #227 - Android Lock Screen 222) Daily Challenge #228 - Best Profit in Single Sale 223) Daily Challenge #229 - Haiku Validator 224) Daily Challenge #230 - Beeramid 225) Daily Challenge #231 - Perfect Powers 226) Daily Challenge #232 - Regex Pattern 227) Daily Challenge #233 - Get Planet Name by ID 228) Daily Challenge #234 - Happy Birthday! 229) Daily Challenge #235 - Reversing a Process 230) Daily Challenge #236 - RGB to Hex Conversion 231) Daily Challenge #237 - Delete Extra Occurrences 232) Daily Challenge #238 - One is the Loneliest Number 233) Daily Challenge #239 - Graceful Tipping 234) Daily Challenge #240 - ATM 235) Daily Challenge #241 - Tip Calculator 236) Daily Challenge #242 - Expressions Matter 237) Daily Challenge #243 - Redacted! 238) Daily Challenge #244 - Search for Letters 239) Daily Challenge #245 - Sort Santa's Reindeer 240) Daily Challenge #246 - Readable Specification Pattern 241) Daily Challenge #247 - Get Planet Name By ID 242) Daily Challenge #248 - Chinese Numerals 243) Daily Challenge #249 - Incremental Changes 244) Daily Challenge #250 - Last Digit of a Large Number 245) Daily Challenge #251 - Largest Number in a Sequence 246) Daily Challenge #252 - Everybody hates Mondays 247) Daily Challenge #253 - Sort Sentences Pseudo-alphabetically 248) Daily Challenge #254 - The Vowel Code 249) Daily Challenge #255 - Is There an Odd Bit? 250) Daily Challenge #256 - How Many Are Smaller Than I? 251) Daily Challenge #257 - Halving Sum 252) Daily Challenge #258 - Ranking Poker Hands 253) Daily Challenge #259 - Duplicate Encoder 254) Daily Challenge #260 - Subtract the Sum 255) Daily Challenge #261 - Diagonal Strings 256) Daily Challenge #262 - No One Likes Spare Change 257) Daily Challenge #263 - Reverse Words 258) Daily Challenge #264 - Digital Root 259) Daily Challenge #265 - Equal Sides 260) Daily Challenge #266 - Who Likes It? 261) Daily Challenge #267 - Braking Speed 262) Daily Challenge #268 - Swapping Characters in Strings 263) Daily Challenge #269 - Decompose n! 264) Daily Challenge #270 - Fix String Case 265) Daily Challenge #271 - Simulate Population Growth 266) Daily Challenge #272 - Printer Errors 267) Daily Challenge #273 - Remove Duplicates 268) Daily Challenge #274 - Aerial Firefighting 269) Daily Challenge #275 - Casino Chips 270) Daily Challenge #276 - Unwanted Dollar Signs 271) Daily Challenge #277 - Over the Road 272) Daily Challenge #278 - Find all non-consecutive numbers 273) Daily Challenge #279 - Playing with Sandpiles 274) Daily Challenge #280 - Driving School 275) Daily Challenge #281 - Area or Perimeter

Setup

Implement a function that will hide the last six digits of each phone number. Your function should be able to understand the separators for US numbers. Phone numbers can be separated by spaces, periods, or hyphens.

Examples

Original: 201-680-0202
Encrypted: `201-6XX-XXXX

Tests

encryptNum("328 6587120")
encryptNum("212-420-0202")
encryptNum("211-458-7851")


This challenge comes from otrebor6 on CodeWars. Thank you to CodeWars, who has licensed redistribution of this challenge under the 2-Clause BSD License!

Want to propose a challenge idea for a future post? Email yo+challenge@dev.to with your suggestions!

Daily Challenge (275 Part Series)

1) Daily Challenge #1 - String Peeler 2) Daily Challenge #2 - String Diamond 3 ... 273 3) Daily Challenge #3 - Vowel Counter 4) Daily Challenge #4 - Checkbook Balancing 5) Daily Challenge #5 - Ten Minute Walk 6) Daily Challenge #6 - Grandma and her friends 7) Daily Challenge #7 - Factorial Decomposition 8) Daily Challenge #8 - Scrabble Word Calculator 9) Daily Challenge #9 - What's Your Number? 10) Daily Challenge #10 - Calculator 11) Daily Challenge #11 - Cubic Numbers 12) Daily Challenge #12 - Next Larger Number 13) Daily Challenge #13 - Twice Linear 14) Daily Challenge #14 - Square into Squares 15) Daily Challenge #15 - Stop gninnipS My sdroW! 16) Daily Challenge #16 - Number of People on the Bus 17) Daily Challenge #17 - Double Trouble 18) Daily Challenge #18 - Triple Trouble 19) Daily Challenge #19 - Turn numbers into words 20) Daily Challenge Post #20 - Number Check 21) Daily Challenge #21 - Human Readable Time 22) Daily Challenge #22 - Simple Pig Latin 23) Daily Challenge #23 - Morse Code Decoder 24) Daily Challenge #24 - Shortest Step 25) Daily Challenge #25 - Double Cola 26) Daily Challenge #26 - Ranking Position 27) Daily Challenge #27 - Unlucky Days 28) Daily Challenge #28 - Kill the Monster! 29) Daily Challenge #29 - Xs and Os 30) Daily Challenge #30 - What is the price? 31) Daily Challenge #31 - Count IPv4 Addresses 32) Daily Challenge #32 - Hide Phone Numbers 33) Daily Challenge #33 - Did you mean...? 34) Daily Challenge #34 - WeIrD StRiNg CaSe 35) Daily Challenge #35 - Find the Outlier 36) Daily Challenge #36 - Let's go for a run! 37) Daily Challenge #37 - Name Swap 38) Daily Challenge #38 - Middle Name 39) Daily Challenge #39 - Virus 40) Daily Challenge #40 - Counting Sheep 41) Daily Challenge #41 - Greed is Good 42) Daily Challenge #42 - Caesar Cipher 43) Daily Challenge #43 - Boardgame Fight Resolver 44) Daily Challenge #44 - Mexican Wave 45) Daily Challenge #45 - Change Machine 46) Daily Challenge #46 - ??? 47) Daily Challenge #47 - Alphabets 48) Daily Challenge #48 - Facebook Likes 49) Daily Challenge #49 - Dollars and Cents 50) Daily Challenge #50 - Number Neighbor 51) Daily Challenge #51 - Valid Curly Braces 52) Daily Challenge #52 - Building a Pyramid 53) Daily Challenge #53 - Faro Shuffle 54) Daily Challenge #54 - What century is it? 55) Daily Challenge #55 - Building a Pile of Cubes 56) Daily Challenge #56 - Coffee Shop 57) Daily Challenge #57 - BMI Calculator 58) Daily Challenge #58 - Smelting Iron Ingots 59) Daily Challenge #59 - Snail Sort 60) Daily Challenge #60 - Find the Missing Letter 61) Daily Challenge #61 - Evolution Rate 62) Daily Challenge #62 - Josephus Survivor 63) Daily Challenge #63- Two Sum 64) Daily Challenge #64- Drying Potatoes 65) Daily Challenge #65- A Disguised Sequence 66) Daily Challenge #66- Friend List 67) Daily Challenge #67- Phone Directory 68) Daily Challenge #68 - Grade Book 69) Daily Challenge #69 - Going to the Cinema 70) Daily Challenge #70 - Pole Vault Competition Results 71) Daily Challenge #71 - See you next Happy Year 72) Daily Challenge #72 - Matrix Shift 73) Daily Challenge #73 - ATM Heist 74) Daily Challenge #74 - Free Pizza 75) Daily Challenge #75 - Set Alarm 76) Daily Challenge #76 - Bingo! (or not...) 77) Daily Challenge #77 - Bird Mountain 78) Daily Challenge #78 - Number of Proper Fractions with Denominator d 79) Daily Challenge #79 - Connect Four 80) Daily Challenge #80 - Longest Vowel Change 81) Daily Challenge #81 - Even or Odd 82) Daily Challenge #82 - English Beggars 83) Daily Challenge #83 - Deodorant Evaporator 84) Daily Challenge #84 - Third Angle of a Triangle 85) Daily Challenge #85 - Unwanted Dollars 86) Daily Challenge #86 - Wouldn't, not Would. 87) Daily Challenge #87 - Pony Express 88) Daily Challenge #88 - Recursive Ninjas 89) Daily Challenge #89 - Extract domain name from URL 90) Daily Challenge #90 - One Step at a Time 91) Daily Challenge #91 - Bananas 92) Daily Challenge #92 - Boggle Board 93) Daily Challenge #93 - Range Extraction 94) Daily Challenge #94 - Last Digit 95) Daily Challenge #95 - CamelCase Method 96) Daily Challenge #96 - Easter Egg Crush Test 97) Daily Challenge #97 - Greed is Good 98) Daily Challenge #98 - Make a Spiral 99) Daily Challenge #99 - Balance the Scales 100) Daily Challenge #100 - Round Up 101) Daily Challenge #101 - Parentheses Generator 102) Daily Challenge #102 - Pentabonacci 103) Daily Challenge #103 - Simple Symbols 104) Daily Challenge #104 - Matrixify 105) Daily Challenge #105 - High-Sum Matrix Drop 106) Daily Challenge #106 - Average Fuel Consumption 107) Daily Challenge #107 - Escape the Mines 108) Daily Challenge #108 - Find the Counterfeit Coin 109) Daily Challenge #109 - Decorate with Wallpaper 110) Daily Challenge #110 - Love VS. Friendship 111) Daily Challenge #111 - 99 Bottles of Beer 112) Daily Challenge #112 - Functions of Integers on the Cartesian Plane 113) Daily Challenge #113 - Iterative Rotation Cipher 114) Daily Challenge #114 - Speed Control 115) Daily Challenge #115 - Look and Say Sequence 116) Daily Challenge #116 - Shortest Knight Path 117) Daily Challenge #117 - MinMinMax 118) Daily Challenge #118 - Reversing a Process 119) Daily Challenge #119 - Adding Big Numbers 120) Daily Challenge #120 - Growth of a Population 121) Daily Challenge #121 - Who has the most money? 122) Daily Challenge #122 - Clockwise Spirals 123) Daily Challenge #123 - Curry me Softly 124) Daily Challenge #124 - Middle Me 125) Daily Challenge #125 - 23 Matches or More 126) Daily Challenge #126 - The Supermarket Line 127) Daily Challenge #127 - Playing with Passphrases 128) Daily Challenge #128 - Blackjack Scorer 129) Daily Challenge #129 - Clay Pigeon Shooting 130) Daily Challenge #130 - GCD Sum 131) Daily Challenge #131 - Remove Anchor from URL 132) Daily Challenge #132 - Is my friend cheating? 133) Daily Challenge #133 - Suitcase Packing 134) Daily Challenge #134 - Rice and Chessboard Problem 135) Daily Challenge #135 - The Wide Mouthed Frog! 136) Daily Challenge #136 - The Deaf Rats of Hamelin 137) Daily Challenge #137 - Help the Bookseller 138) Daily Challenge #138 - Do I get a Bonus? 139) Daily Challenge #138 - Keep Up the Hoop 140) Daily Challenge #140 - I love you, a little, a lot, passionately ... not at all 141) Daily Challenge #141 - Two Sum 142) Daily Challenge #142 - Parts of a Whole 143) Daily Challenge #143 - Big Arithmetic 144) Daily Challenge #144 - Box Office Clerk 145) Daily Challenge #145 - SET Card Game 146) Daily Challenge #146 - The Dollar Game 147) Daily Challenge #147 - NIM 148) Daily Challenge #148 - Disemvowel Trolls 149) Daily Challenge #149 - Fun with Lamps 150) Daily Challenge #150 - Boggle Guess Validator 151) Daily Challenge #151 - Reverse Parentheses 152) Daily Challenge #152 - Strongest Number in an Interval 153) Daily Challenge #153 - Horse Race Gamble 154) Daily Challenge #154 - Stable Arrangement 155) Daily Challenge #155 - Royal Arranged Marriages 156) Daily Challenge #162 - Taxi Dispatching 157) Daily Challenge #163 - Significant Figures 158) Daily Challenge #164 - Jump 159) Daily Challenge #165 - Password Lost in a Grid 160) Daily Challenge #166 - Cat and Mouse 161) Daily Challenge #167 - Return String As Sorted Blocks 162) Daily Challenge #168 - [Code golf] f (f (f b)) = f b 163) Daily Challenge #169 - Christmas Tree 164) Daily Challenge #170 - Pokemon Damage Calculator 165) Daily Challenge #171 - Ordering Beers in Poland 166) Daily Challenge #172 - Find All in an Array 167) Daily Challenge #173 - Pandemia 168) Daily Challenge #174 - Soccer League Table 169) Daily Challenge #175 - Complementary DNA 170) Daily Challenge #176 - Loopover 171) Daily Challenge #177 - Supersize Me 172) Daily Challenge #178 - Create Phone Numbers 173) Daily Challenge #179 - Hide Phone Numbers 174) Daily Challenge #180 - SMS Shortener 175) Daily Challenge #181 - Is King in Check? 176) Daily Challenge #182 - Arrh, grabscrab! 177) Daily Challenge #183 - Automorphic Numbers 178) Daily Challenge #184 - Form the Minimum 179) Daily Challenge #185 - House Numbers Sum 180) Daily Challenge #186 - Jumping Frog 181) Daily Challenge #187 - Most Sales 182) Daily Challenge #188 - Break camelCase 183) Daily Challenge #189 - Convert Number into Reversed Array 184) Daily Challenge #190 - capitalizeFirstLast 185) Daily Challenge #191 - Alphabetical Addition 186) Daily Challenge #192 - Can you Survive the Zombies? 187) Daily Challenge #193 - What's the Real Floor? 188) Daily Challenge #194 - Spread Number 189) Daily Challenge #195 - No Zeroes for Heroes 190) Daily Challenge #196 - Flou 191) Daily Challenge #197 - Population Growth 192) Daily Challenge #198 - 21 Blackjack 193) Daily Challenge #199 - List of All Rationals 194) Daily Challenge #200 - Longest Linear Palindromic Substring 195) Daily Challenge #201 - Complete the Pattern 196) Daily Challenge #202 - Complete the Pattern II 197) Daily Challenge #203 - Pascal's Triangle 198) Daily Challenge #204 - Partial Keys 199) Daily Challenge #205 - Consonant String Value 200) Daily Challenge #206 - Pound Means Backspace 201) Daily Challenge #207 - Snakes and Ladders 202) Daily Challenge #208 - Delete Occurrences of an Element 203) Daily Challenge #209 - Roman Numerals 204) Daily Challenge #210 - Separate Capitalization 205) Daily Challenge #211 - Product Partitions 206) Daily Challenge #212 - DNA to RNA 207) Daily Challenge #213 - Are they the "same"? 208) Daily Challenge #214 - Persistent Bugger 209) Daily Challenge #215 - Difference of 2 210) Daily Challenge #216 - Rainfall 211) Daily Challenge #217 - SMS w/ an Old Phone 212) Daily Challenge #218 - Possible Sides of a Non-Right Triangle 213) Daily Challenge #219 - Compare Strings 214) Daily Challenge #220 - What Dominates Your Array? 215) Daily Challenge #221 - The Merchant of York 216) Daily Challenge #222 - Parse Bank Account Numbers 217) Daily Challenge #223 - Responsible Drinking 218) Daily Challenge #224 - Password Validator 219) Daily Challenge #225 - Square'n'Sum 220) Daily Challenge #226 - Array to HTML Table 221) Daily Challenge #227 - Android Lock Screen 222) Daily Challenge #228 - Best Profit in Single Sale 223) Daily Challenge #229 - Haiku Validator 224) Daily Challenge #230 - Beeramid 225) Daily Challenge #231 - Perfect Powers 226) Daily Challenge #232 - Regex Pattern 227) Daily Challenge #233 - Get Planet Name by ID 228) Daily Challenge #234 - Happy Birthday! 229) Daily Challenge #235 - Reversing a Process 230) Daily Challenge #236 - RGB to Hex Conversion 231) Daily Challenge #237 - Delete Extra Occurrences 232) Daily Challenge #238 - One is the Loneliest Number 233) Daily Challenge #239 - Graceful Tipping 234) Daily Challenge #240 - ATM 235) Daily Challenge #241 - Tip Calculator 236) Daily Challenge #242 - Expressions Matter 237) Daily Challenge #243 - Redacted! 238) Daily Challenge #244 - Search for Letters 239) Daily Challenge #245 - Sort Santa's Reindeer 240) Daily Challenge #246 - Readable Specification Pattern 241) Daily Challenge #247 - Get Planet Name By ID 242) Daily Challenge #248 - Chinese Numerals 243) Daily Challenge #249 - Incremental Changes 244) Daily Challenge #250 - Last Digit of a Large Number 245) Daily Challenge #251 - Largest Number in a Sequence 246) Daily Challenge #252 - Everybody hates Mondays 247) Daily Challenge #253 - Sort Sentences Pseudo-alphabetically 248) Daily Challenge #254 - The Vowel Code 249) Daily Challenge #255 - Is There an Odd Bit? 250) Daily Challenge #256 - How Many Are Smaller Than I? 251) Daily Challenge #257 - Halving Sum 252) Daily Challenge #258 - Ranking Poker Hands 253) Daily Challenge #259 - Duplicate Encoder 254) Daily Challenge #260 - Subtract the Sum 255) Daily Challenge #261 - Diagonal Strings 256) Daily Challenge #262 - No One Likes Spare Change 257) Daily Challenge #263 - Reverse Words 258) Daily Challenge #264 - Digital Root 259) Daily Challenge #265 - Equal Sides 260) Daily Challenge #266 - Who Likes It? 261) Daily Challenge #267 - Braking Speed 262) Daily Challenge #268 - Swapping Characters in Strings 263) Daily Challenge #269 - Decompose n! 264) Daily Challenge #270 - Fix String Case 265) Daily Challenge #271 - Simulate Population Growth 266) Daily Challenge #272 - Printer Errors 267) Daily Challenge #273 - Remove Duplicates 268) Daily Challenge #274 - Aerial Firefighting 269) Daily Challenge #275 - Casino Chips 270) Daily Challenge #276 - Unwanted Dollar Signs 271) Daily Challenge #277 - Over the Road 272) Daily Challenge #278 - Find all non-consecutive numbers 273) Daily Challenge #279 - Playing with Sandpiles 274) Daily Challenge #280 - Driving School 275) Daily Challenge #281 - Area or Perimeter

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Discussion

markdown guide
 

JavaScript:

const encryptNum = num => num.replace(/(\d[ .-]?){6}$/, x => x.replace(/\d/g, 'X'))

The first replace finds the last 6 digits, with or without trailing separators.
The resulting match undergoes another replace call to substitute any digits for X's.

The first expression can also be relaxed to allow any separators: /(\d[^\d]?){6}$/, or even any number of separators: /(\d[^\d]*){6}$/.

 
 
 

Javascript

function encryptNum(num){
  return num.substr(0, 5) + 'XX-XXXX'
}
 

This only works if you're expecting a certain value. Output would be weird otherwise.

 

Yeah, but the data validation is not required in this challange.

True, but it does expect the tests to all pass still, which they won't with that solution

 

Nice short solution!

If I'm being correct, for the string "328 6587120", the expected output should be "328 6XXXXXX".

But in your case, the output would be "328 6XX-XXXX".

 

Rust:

fn encrypt_num(phone_number: String) -> String {
    let mut bytes = phone_number.into_bytes();
    for ch in bytes.iter_mut().rev().filter(|b| {
        let c = **b as char;
        '0' <= c && c <= '9'
    }).take(6) {
        *ch = 'X' as u8;
    }
    String::from_utf8(bytes).unwrap()
}

fn main() {
    assert_eq!(encrypt_num("328 6587120".to_owned()), "328 6XXXXXX");
    assert_eq!(encrypt_num("212-420-0202".to_owned()), "212-4XX-XXXX");
    assert_eq!(encrypt_num("211-458-7851".to_owned()), "211-4XX-XXXX");
}
 

Elm

encryptDigit : Char -> Char
encryptDigit character =
    if Char.isDigit character then
        'X'

    else
        character


encryptNum : String -> String
encryptNum string =
    String.map encryptDigit ( String.dropLeft 5 string )
        |> String.append ( String.left 5 string )
 

JavaScript

If we want all the phone numbers to have the same format, we could use a regular expression to detect all the digits (assuming that the phone number is correct) and format it accordingly:

const encryptNum = (num) => {
  const nums = num.match(/\d/gi).join("");
  return `${nums.substring(0,3)}-${nums.substring(3,6)}-${nums.substring(6)}`;
}

If we want to keep the original format (and again, assuming the phone number is correct), another solution would be transforming the string into an array (strings are immutable, an array would be easier to operate), parse the last 6 digits and return its concatenation:

const encryptNum = (num) => {
  let numbers = 0;
  let position = num.length - 1;
  let formattedNum = num.split("");

  while (numbers < 6 && position > 0) {
    if (num[position] >= "0" && num[position] <= "9") { 
      formattedNum[position] = "x";
      numbers++;
    }
    position--;
  }

  return formattedNum.join("");
}
 

Haskell, similar idea to my solution in Ruby

import Data.Char (isDigit)

encryptNum :: String -> String
encryptNum = reverse . encryptDigit 0 . reverse
    where
        encryptDigit 6 xs     = xs
        encryptDigit i (x:xs) | isDigit x = 'X' : encryptDigit (i+1) xs
                              | otherwise =  x  : encryptDigit i xs
 

Scala,

def encryptNum(input : String) = {
  def encryptInner(remain : Int, toGo : List[Char]) : List[Char] = {
    toGo match {
      case Nil => Nil
      case _ if remain == 0 => toGo
      case x::xs if x.isDigit => 'X' :: encryptInner(remain - 1, xs)
      case x::xs => x :: encryptInner(remain, xs)
    }
  }

  encryptInner(6, input.reverse.toList).reverse.mkString
}
 

Python, a straightforward approach that would be fast to design and implement without bugs during an interview. It is big-O optimal and easy to understand and refactor.

def encrypt(phone_num):
  # define some const. easy to refactor into method sig or config elsewhere later
  ENCRYPT_NUMBER = 6
  ENCRYPT_SYMBOL = 'X'

  # we'll return this at the end - reversed and joined.
  encrypted = []
  # count the numbers we encrypt
  counter = 0

  # start at the end and encrypt numbers until we reach ENCRYPT_NUMBER
  for ch in phone_num[::-1]:
    # we're done encrypting so pass everything along
    if counter == ENCRYPT_NUMBER:
      encrypted.append(ch)
      continue

    try:
      # if character is a number, encrypt it
      int(ch)
      counter += 1
      encrypted.append(ENCRYPT_SYMBOL)
    except ValueError:
      # character is not a number so pass it  through
      encrypted.append(ch)

  # return a string in the right order
  return ''.join(encrypted[::-1])

print(encrypt("328 6587120")) # 328 6XXXXXX
print(encrypt("212-420-0202")) # 212-4XX-XXXX
print(encrypt("211-458-7851")) # 211-4XX-XXXX
print(encrypt("211 458 7851")) # 211 4XX XXXX
print(encrypt("2114587851")) # 2114XXXXXX
 

ONE REGEX TO RULE THEM

Put your separators where you want! I'll find them all.

const encryptNum = num => num.replace(/((\d[-\s.]?){4})(\d)([\s.-]?)(\d)([\s.-]?)(\d)([\s.-]?)(\d)([\s.-]?)(\d)([\s.-]?)(\d)/, '$1X$4X$6X$8X$10X$12X');
 

Dart - not a fan of being creative.

String encryptNum(String phoneNum) {
  var regexp = RegExp(r"([0-9- .]+)");
  var result = regexp?.firstMatch(phoneNum)?.group(0);
  result = result?.replaceAll(new RegExp(r"(\.|-|\s)"), "");
  if(result.length == 10) {
    var val = StringBuffer();
    for(var idx = 0; idx < result.length; idx++) {
      if(idx < 4) {
        val.write(result[idx]);
      } else {
        val.write("X");
      }
      switch(idx) {
        case 2:
        case 5:
          val.write("-");
        break;
      }
    }
    return val.toString();
  }
  return null;
}
print(encryptNum("142 424 2142"));
print(encryptNum("142 424-2142"));
print(encryptNum("142 424.2142"));
print(encryptNum("142 4242142"));
print(encryptNum("142-424-2142"));
print(encryptNum("142-424 2142"));
print(encryptNum("142-424.2142"));
print(encryptNum("142-4242142"));
print(encryptNum("142.424 2142"));
print(encryptNum("142.424-2142"));
print(encryptNum("142.424.2142"));
print(encryptNum("142.4242142"));
print(encryptNum("142424-2142"));
print(encryptNum("142424.2142"));
print(encryptNum("142424 2142"));
print(encryptNum("1424242142"));
 

JavaScript solution:

const encryptNum = num => {
    num = num.replace(/[-,\s]/g,"");
    return `${num.substring(0,3)}-${num.substring(3,4)}XX-XXXX`
}
 

Ruby

def encryptNum num
    num.reverse!.gsub(/\d/).with_index { |d, i| i < 6 ? 'X' : d }.reverse!
end
 

My basic solution in JS: Reverse string then replace with 'X' and count to 6

 

Didn't even know you can embed into comments, that's really cool.

Do you not feel that solution is overcomplicating it?