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// 1074. Number of Submatrices That Sum to Target
#include "leetcode.h"
/*
* given a 'matrix' and 'target', return the number of non-empty submatrices
* that sum to target. a submatrix 'x1, y1 x2, y2' is the set of all cells
* 'matrix[x][y]' with 'x1 <= x <= x2' and 'y1 <= y <= y2'. two submatrices are
* different if they have some coordinate that is different. for example if x1
* != x1
*/
int numSubmatrixSumTarget(int **matrix, int matrix_size, int *matrix_col_size,
int target) {
int r_size = matrix_col_size[0], dp[r_size], ans = 0, y = 0;
while (y < matrix_size) {
memset(dp, 0, sizeof(int) * r_size);
for (int row = y; row < matrix_size; row++)
for (int col = 0; col < r_size; col++)
dp[col] += matrix[row][col];
for (int col = 0; col < r_size; col++) {
int sum = 0;
for (int _col = col; _col < r_size; _col++) {
sum += dp[_col];
if (sum == target)
ans++;
}
}
y++;
}
return ans;
}
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