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Daily Challenge #119 - Adding Big Numbers

thepracticaldev profile image dev.to staff ・1 min read

Daily Challenge (273 Part Series)

1) Daily Challenge #1 - String Peeler 2) Daily Challenge #2 - String Diamond 3 ... 271 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

We need to sum big numbers and we require your help.

Write a function that returns the sum of two numbers. The input numbers are strings and the function must return a string.

Example:

add("123", "321"); -> "444"
add("11", "99"); -> "110"

Notes:

  • The input numbers are big.
  • The input is a string of only digits
  • The numbers are positives

This challenge comes from Becojo 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!

Discussion

markdown guide
 
 

Typescript includes tests

github.com/kiliman/dev-to-daily-ch...

export const add = (a: string, b: string): string => {
  const re = /^\d+$/
  if (!re.test(a) || !re.test(b)) {
    throw new Error(`{a} and {b} must be positive integers`)
  }

  const result = []
  a = a
    .split('')
    .reverse()
    .join('')
  b = b
    .split('')
    .reverse()
    .join('')
  let carry = 0
  for (let i = 0; i < Math.max(a.length, b.length); i++) {
    const a_ = a.length > i ? parseInt(a[i]) : 0
    const b_ = b.length > i ? parseInt(b[i]) : 0
    let sum = a_ + b_ + carry
    carry = Math.floor(sum / 10)
    if (carry !== 0) {
      sum = sum % 10
    }
    result.push(String(sum))
  }
  if (carry > 0) {
    result.push(carry)
  }
  return result.reverse().join('')
}

Test

import { add } from '.'

it('should throw an error if numbers are not all digits', () => {
  expect(() => add('', '')).toThrow()
  expect(() => add('abc', '321')).toThrow()
  expect(() => add('11', 'xyz')).toThrow()
})

it('should return sum of two numbers', () => {
  expect(add('0', '0')).toBe('0')
  expect(add('123', '321')).toBe('444')
  expect(add('11', '99')).toBe('110')
  expect(add('1', '199')).toBe('200')
})

it('should return sum of two really big numbers', () => {
  expect(add('123456789', '987654321')).toBe('1111111110')
  expect(add('12345678910123456789', '987654323109876543210')).toBe(
    '1000000002019999999999',
  )
})
 

Python for arbitrarily large numbers represented as strings:

def large_sum(a: str, b: str) -> str:

    if len(b) < len(a):
        return large_sum(b, a)

    alist = [int(c) for c in reversed(a)]
    blist = [int(c) for c in reversed(b)]

    for _ in range(0, len(alist) - len(blist)):
        blist.append(0)

    overflow = 0
    output = []
    for ax, bx in zip(alist, blist):
        sumval = ax + bx + overflow
        overflow = int((sumval) / 10)
        output.append(sumval % 10)

    if overflow != 0:
        output.append(overflow)

    return "".join(str(i) for i in reversed(output))


print(large_sum("1234", "3456"))
print(
    large_sum(
        "1234567890123456789012345678901234567890",
        "456789012345678901234567890123456789012345678901234567890123",
    )
)
print(large_sum("44", "2"))

 

Java


import java.math.BigDecimal;

class Adder {
    public static String add(String arg1, String arg2) {
        return new BigDecimal(arg1).add(new BigDecimal(arg2)).toString();
    }
}

 

There's a BigInt type in vanilla javascript, why not just use that instead?

const add = (a, b) => (BigInt(a) + BigInt(b)).toString();
add("10000000000000000000", "3");   // 10000000000000000003
 

Here is the simple solution with JavaScript:

function add(a, b) {
  var ans = "";

  if (a.length > b.length ) {
    var zeroLength = a.length - b.length;

    for (var index=0; index<zeroLength; index++) {
      b = "0" + b;
    }
  }

  if (a.length < b.length ) {
    var zeroLength = b.length - a.length;

    for (var index=0; index<zeroLength; index++) {
      a = "0" + a;
    }
  }

  var step = [];
  if (a.length === b.length) {
    for (var index=a.length-1; index>=0; index--) {
      var numberA = Number(a[index]);
      var numberB = Number(b[index]);
      var addResult = 0;
      if (step[index+1]) {
        addResult = step[index+1] + numberA + numberB;
      } else {
        addResult = numberA + numberB;
      }
      if (addResult >= 10 && index !== 0) {
        ans = String(addResult - 10) + ans;
        step[index] = 1;
      } else {
        ans = String(addResult) + ans;
      }
    }
  }

  return ans;
}
 

Javascript

add = (x, y) => {
    const l = Math.max(x.length, y.length);
    const r = Array(l).fill().reduce(
        (a, _, i) => [
            (a[1] + +(x[x.length - 1 - i] || '0') + +(y[y.length - 1 - i] || '0')) % 10 + a[0],
            +((a[1] + +(x[x.length - 1 - i] || '0') + +(y[y.length - 1 - i] || '0')) > 9)
        ],
        ['', 0]);
    return '' + (r[1] ? r[1] : '') + r[0]
}
 

Rust:

fn add(num1: &str, num2: &str) -> Result<String, String> {
    const ZERO_CHAR: u8 = '0' as u8;
    let mut reversed_result = Vec::<u8>::new();
    let max_digits = num1.len().max(num2.len());

    macro_rules! convert_num {
        ($num:expr) => {
            $num.chars().rev().chain(['0'].iter().cloned().cycle())
        }
    }

    let digits1 = convert_num!(num1);
    let digits2 = convert_num!(num2);

    let mut carry = 0;
    for (digit1, digit2) in digits1.zip(digits2).take(max_digits) {
        fn digit_to_numeric(digit: char) -> Result<u8, String> {
            if '0' <= digit && digit <= '9' {
                Ok(digit as u8 - ZERO_CHAR)
            } else {
                Err(format!("{:?} is not a digit", digit))
            }
        }

        let digit1 = digit_to_numeric(digit1)?;
        let digit2 = digit_to_numeric(digit2)?;

        let digit_sum = digit1 + digit2 + carry;
        carry = digit_sum / 10;
        assert!(carry < 10);
        reversed_result.push(digit_sum % 10 + ZERO_CHAR);
    }
    if 0 < carry {
        reversed_result.push(carry + ZERO_CHAR);
    }
    reversed_result.reverse();
    Ok(String::from_utf8(reversed_result).expect("We only added digits"))
}
 

Swift function :

func sum(first: String, second: String) -> String {
    return "\((Int(first) ?? 0) + (Int(second) ?? 0))"
}

And with a closure :

let _ = { (first: String, second: String) -> String in
    "\((Int(first) ?? 0) + (Int(second) ?? 0))"
}
 

Isn't Int a sized integer? It won't work with numbers that don't fit in 64 bits (or 32 bits, if you compile it for 32 bit architectures)

 

A more cool JS solution:

add = (x, y) => (BigInt(x) + BigInt(y)).toString(10)
 

python

def add(a, b):
    return (f'{int(a)+int(b)}')
 

Ruby:

def add(a, b)
    (a.to_i + b.to_i).to_s
end
 

JS

add = (one, tew)=>{return (Number(one) + Number(tew)).toString()}

||

add2 = (...input) =>{ return input.reduce((acc,curr)=>{return (acc + Number(curr)).toString()})}