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Daily Coding Challenge #51

wingkwong profile image Wing-Kam ・3 min read

Daily Coding Challenge (88 Part Series)

1) Daily Coding Challenge #1 2) Daily Coding Challenge #2 3 ... 86 3) Daily Coding Challenge #3 4) Daily Coding Challenge #4 5) Daily Coding Challenge #5 6) Daily Coding Challenge #6 7) Daily Coding Challenge #7 8) Daily Coding Challenge #8 9) Daily Coding Challenge #9 10) Daily Coding Challenge #10 11) Daily Coding Challenge #11 12) Daily Coding Challenge #12 13) Daily Coding Challenge #13 14) Daily Coding Challenge #14 15) Daily Coding Challenge #15 16) Daily Coding Challenge #16 17) Daily Coding Challenge #17 18) Daily Coding Challenge #18 19) Daily Coding Challenge #19 20) Daily Coding Challenge #20 21) Daily Coding Challenge #21 22) Daily Coding Challenge #22 23) Daily Coding Challenge #23 24) Daily Coding Challenge #24 25) Daily Coding Challenge #25 26) Daily Coding Challenge #26 27) Daily Coding Challenge #27 28) Daily Coding Challenge #28 29) Daily Coding Challenge #29 30) Daily Coding Challenge #30 31) Daily Coding Challenge #31 32) Daily Coding Challenge #32 33) Daily Coding Challenge #33 34) Daily Coding Challenge #34 35) Daily Coding Challenge #35 36) Daily Coding Challenge #36 37) Daily Coding Challenge #37 38) Daily Coding Challenge #38 39) Daily Coding Challenge #39 40) Daily Coding Challenge #40 41) Daily Coding Challenge #41 42) Daily Coding Challenge #42 43) Daily Coding Challenge #43 44) Daily Coding Challenge #44 45) Daily Coding Challenge #45 46) Daily Coding Challenge #46 47) Daily Coding Challenge #47 48) Daily Coding Challenge #48 49) Daily Coding Challenge #49 50) Daily Coding Challenge #50 51) Daily Coding Challenge #51 52) Daily Coding Challenge #52 53) Daily Coding Challenge #53 54) Daily Coding Challenge #54 55) Daily Coding Challenge #55 56) Daily Coding Challenge #56 57) Daily Coding Challenge #57 58) Daily Coding Challenge #58 59) Daily Coding Challenge #59 60) Daily Coding Challenge #60 61) Daily Coding Challenge #61 62) Daily Coding Challenge #62 63) Daily Coding Challenge #63 64) Daily Coding Challenge #64 65) Daily Coding Challenge #65 66) Daily Coding Challenge #66 67) Daily Coding Challenge #67 68) Daily Coding Challenge #68 69) Daily Coding Challenge #69 70) Daily Coding Challenge #70 71) Daily Coding Challenge #71 72) Daily Coding Challenge #72 73) Daily Coding Challenge #73 74) Daily Coding Challenge #74 75) Daily Coding Challenge #75 76) Daily Coding Challenge #76 77) Daily Coding Challenge #77 78) Daily Coding Challenge #78 79) Daily Coding Challenge #79 80) Daily Coding Challenge #80 81) Daily Coding Challenge #81 82) Daily Coding Challenge #82 83) Daily Coding Challenge #83 84) Daily Coding Challenge #84 85) Daily Coding Challenge #85 86) Daily Coding Challenge #86 87) Daily Coding Challenge #87 88) Daily Coding Challenge #88

About

This is a series of Daily Coding Challenge. Each day I show a few solutions written in C++. The questions are from coding practice/contest sites such as HackerRank, LeetCode, Codeforces, Atcoder and etc.


/*
LeetCode - Arranging Coins

You have a total of n coins that you want to form in a staircase shape, where every k-th row must have exactly k coins.

Given n, find the total number of full staircase rows that can be formed.

n is a non-negative integer and fits within the range of a 32-bit signed integer.

Example 1:

n = 5

The coins can form the following rows:
¤
¤ ¤
¤ ¤

Because the 3rd row is incomplete, we return 2.
Example 2:

n = 8

The coins can form the following rows:
¤
¤ ¤
¤ ¤ ¤
¤ ¤

Because the 4th row is incomplete, we return 3.
*/

class Solution {
public:
    int arrangeCoins(int n) {
        // gauss' formula
        // k(k+1)/2<=n
        // k(k+1/2)^2-1/4<=n
        // k=sqrt(2n+1/4)-1/2
        return sqrt(2*(long long)n+0.25)-0.5;
    }
};

/*
LeetCode - Prison Cells After N Days

There are 8 prison cells in a row, and each cell is either occupied or vacant.

Each day, whether the cell is occupied or vacant changes according to the following rules:

If a cell has two adjacent neighbors that are both occupied or both vacant, then the cell becomes occupied.
Otherwise, it becomes vacant.
(Note that because the prison is a row, the first and the last cells in the row can't have two adjacent neighbors.)

We describe the current state of the prison in the following way: cells[i] == 1 if the i-th cell is occupied, else cells[i] == 0.

Given the initial state of the prison, return the state of the prison after N days (and N such changes described above.)

Example 1:

Input: cells = [0,1,0,1,1,0,0,1], N = 7
Output: [0,0,1,1,0,0,0,0]
Explanation: 
The following table summarizes the state of the prison on each day:
Day 0: [0, 1, 0, 1, 1, 0, 0, 1]
Day 1: [0, 1, 1, 0, 0, 0, 0, 0]
Day 2: [0, 0, 0, 0, 1, 1, 1, 0]
Day 3: [0, 1, 1, 0, 0, 1, 0, 0]
Day 4: [0, 0, 0, 0, 0, 1, 0, 0]
Day 5: [0, 1, 1, 1, 0, 1, 0, 0]
Day 6: [0, 0, 1, 0, 1, 1, 0, 0]
Day 7: [0, 0, 1, 1, 0, 0, 0, 0]

Example 2:

Input: cells = [1,0,0,1,0,0,1,0], N = 1000000000
Output: [0,0,1,1,1,1,1,0]


Note:

cells.length == 8
cells[i] is in {0, 1}
1 <= N <= 10^9
*/

class Solution {
public:
    vector<int> prisonAfterNDays(vector<int>& cells, int N) {
        // Every 14 days the cells will be same 
        // i.e. 6C2-1 (6 cells as the first and the last don't change, 2 states - 0 or 1)
        N = (N%14==0)?14:N%14;
        for(int i=0;i<N;i++){
            vector<int> tmp(8,0);
            for(int j=1;j<7;j++){
                // cells[i] == 1 if the i-th cell is occupied, else cells[i] == 0
                // cells[0] and cells[7] are always 0
                tmp[j]=(cells[j-1]==cells[j+1])?1:0;
            }
            cells=tmp;
        }
        return cells;
    }
};

The source code is available in corresponding repo below. Star and watch for timely updates!

GitHub logo wingkwong / leetcode

🏆 A Collection of my LeetCode Solutions with Explanations 🏆

GitHub logo wingkwong / hackerrank

🏆 A Collection of my HackerRank Solutions with Explanations 🏆

GitHub logo wingkwong / codeforces

🏆 A Collection of my Codeforces Solutions with Explanations 🏆

GitHub logo wingkwong / atcoder

🏆 A Collection of my AtCoder Solutions with Explanations 🏆

Daily Coding Challenge (88 Part Series)

1) Daily Coding Challenge #1 2) Daily Coding Challenge #2 3 ... 86 3) Daily Coding Challenge #3 4) Daily Coding Challenge #4 5) Daily Coding Challenge #5 6) Daily Coding Challenge #6 7) Daily Coding Challenge #7 8) Daily Coding Challenge #8 9) Daily Coding Challenge #9 10) Daily Coding Challenge #10 11) Daily Coding Challenge #11 12) Daily Coding Challenge #12 13) Daily Coding Challenge #13 14) Daily Coding Challenge #14 15) Daily Coding Challenge #15 16) Daily Coding Challenge #16 17) Daily Coding Challenge #17 18) Daily Coding Challenge #18 19) Daily Coding Challenge #19 20) Daily Coding Challenge #20 21) Daily Coding Challenge #21 22) Daily Coding Challenge #22 23) Daily Coding Challenge #23 24) Daily Coding Challenge #24 25) Daily Coding Challenge #25 26) Daily Coding Challenge #26 27) Daily Coding Challenge #27 28) Daily Coding Challenge #28 29) Daily Coding Challenge #29 30) Daily Coding Challenge #30 31) Daily Coding Challenge #31 32) Daily Coding Challenge #32 33) Daily Coding Challenge #33 34) Daily Coding Challenge #34 35) Daily Coding Challenge #35 36) Daily Coding Challenge #36 37) Daily Coding Challenge #37 38) Daily Coding Challenge #38 39) Daily Coding Challenge #39 40) Daily Coding Challenge #40 41) Daily Coding Challenge #41 42) Daily Coding Challenge #42 43) Daily Coding Challenge #43 44) Daily Coding Challenge #44 45) Daily Coding Challenge #45 46) Daily Coding Challenge #46 47) Daily Coding Challenge #47 48) Daily Coding Challenge #48 49) Daily Coding Challenge #49 50) Daily Coding Challenge #50 51) Daily Coding Challenge #51 52) Daily Coding Challenge #52 53) Daily Coding Challenge #53 54) Daily Coding Challenge #54 55) Daily Coding Challenge #55 56) Daily Coding Challenge #56 57) Daily Coding Challenge #57 58) Daily Coding Challenge #58 59) Daily Coding Challenge #59 60) Daily Coding Challenge #60 61) Daily Coding Challenge #61 62) Daily Coding Challenge #62 63) Daily Coding Challenge #63 64) Daily Coding Challenge #64 65) Daily Coding Challenge #65 66) Daily Coding Challenge #66 67) Daily Coding Challenge #67 68) Daily Coding Challenge #68 69) Daily Coding Challenge #69 70) Daily Coding Challenge #70 71) Daily Coding Challenge #71 72) Daily Coding Challenge #72 73) Daily Coding Challenge #73 74) Daily Coding Challenge #74 75) Daily Coding Challenge #75 76) Daily Coding Challenge #76 77) Daily Coding Challenge #77 78) Daily Coding Challenge #78 79) Daily Coding Challenge #79 80) Daily Coding Challenge #80 81) Daily Coding Challenge #81 82) Daily Coding Challenge #82 83) Daily Coding Challenge #83 84) Daily Coding Challenge #84 85) Daily Coding Challenge #85 86) Daily Coding Challenge #86 87) Daily Coding Challenge #87 88) Daily Coding Challenge #88

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wingkwong profile

Wing-Kam

@wingkwong

Consultant by day. Developer by night. AWS certified. Exploring #CloudNative currently.

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