1582. Special Positions in a Binary Matrix
Given an m x n binary matrix mat, return the number of special positions in mat.
A position (i, j) is called special if mat[i][j] == 1 and all other elements in row i and column j are 0 (rows and columns are 0-indexed).
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| class Solution {
public:
int numSpecial(vector<vector<int>>& mat) {
int n = mat.size(), m = mat[0].size();
vector<int> r(n), c(m);
for(int i = 0; i < n; i++) for(int j = 0; j < m; j++) {
r[i] += mat[i][j];
c[j] += mat[i][j];
}
int res = 0;
for(int i = 0; i < n; i++) for(int j = 0; j < m; j++) {
res += (r[i] == 1 and c[j] == 1 and mat[i][j] == 1);
}
return res;
}
};
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