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// 1572. Matrix Diagonal Sum
#include "leetcode.h"
/*
* given a square matrix 'mat', return the sum of the matrix
* diagonals. only include the sum of all the elements on the
* primary diagonal and all the elements on the secondary
* diagonal that are not part of the primary
*/
class Solution {
public:
int diagonalSum(vvd & mat) {
int n = mat.size(), ans = 0;
for (int i = 0; i < n; i++) {
if (i != n - i - 1)
ans += mat[i][i] + mat[i][n - i - 1];
else
ans += mat[i][i];
}
return ans;
}
};
int main() {
Solution obj;
vvd m1 = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}};
vvd m2 = {{1, 1, 1, 1}, {1, 1, 1, 1}, {1, 1, 1, 1}, {1, 1, 1, 1}};
vvd m3 = {{5}};
printf("%d\n", obj.diagonalSum(m1)); // expect: 25
printf("%d\n", obj.diagonalSum(m2)); // expect: 8
printf("%d\n", obj.diagonalSum(m3)); // expect: 5
}
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