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| class Solution {
public long numberOfRightTriangles(int[][] grid) {
int m = grid.length, n = grid[0].length;
int[] rows = new int[m];
int[] cols = new int[n];
for (int i = 0; i < m; ++i) {
for (int j = 0; j < n; ++j) {
rows[i] += grid[i][j];
cols[j] += grid[i][j];
}
}
long ans = 0;
for (int i = 0; i < m; ++i) {
for (int j = 0; j < n; ++j) {
if (grid[i][j] == 1) {
ans += (rows[i] - 1) * (cols[j] - 1);
}
}
}
return ans;
}
}
|
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