Question

Imagine your 2d vector is a chess board with alternating squares of white and black ( google for chess board if you don't know what one looks like ).

Write a method whiteMinusBlackSquares( vector<vector<int>> numbers ) that returns an integer.

return the sum of all values 'on' white squares minus the sum of all values 'on' black squares.

For example, the top left (0,0) square is white.

If I pass a vector<vector<int>> of { 1, 2, 3, 4 }, {5, 6, 7, 8}, {9,10, 11, 12}, { 13, 14, 15, 16}

1 and 3 would be on white squares in the first row

6 and 8 woudl be on white squares in the second row

9 and 11 would be on white squares in the third row

and 14 and 16 woudl be on white squares in the fourth row.

Answer 1

#include <iostream>
#include <vector>

using namespace std;

int whiteMinusBlackSquares( vector< vector< int > > numbers ) {
        int whites = 0;
        int blacks = 0;

        for(int i=0; i < numbers.size(); i++) {
                bool white = (i % 2 == 0);
                
                for(int j=0; j<numbers[i].size(); j++) {
                        if(white) {
                                whites += numbers[i][j];
                        } else {
                                blacks += numbers[i][j];
                        }
                        white = !white;
                }

        }

        return whites - blacks;
}

int main() {
        vector< vector< int > > of{{ 1, 2, 3, 4 }, {5, 6, 7, 8}, {9,10, 11, 12}, { 13, 14, 15, 16}};

        cout << whiteMinusBlackSquares(of) << endl;
}

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clang version 7.0.0-3~ubun final) clang++-7-pthread -o ma . ./main int whiteMinusBlackSquares vector< vector< int > > numbers ) { 39 int whites = 0; int blacks = 0; 40 41 42 for (int i-0; i < numbers.size(); i++ { bool white = (i % 2 == 0); 43 44 45 for (int j-0; j<numbers[i].size(); j++) { 46 if (white) 47 numbers[i]jl whites + 48 }else f 49 blacks +n umbers [i] [j]; 50 51 white white; 52 53 54 55 56 return whites - blacks; 57 58 59 int main() { 60 vector< vector< int > > of{{ 1, 2, 3, 4 }, {5, 6, 7, 8}, {9,10, 11, 12}, { 13, 14, 61 15, 16} 62 << endl cout <whiteMinusBlackSquares (of) 63 64