1582. Special Positions in a Binary Matrix #

class Solution {
    public int numSpecial(int[][] mat) {
        Map<Integer, Integer> cntRows = new HashMap<>();
        Map<Integer, Integer> cntCols = new HashMap<>();
        for (int i = 0; i < mat.length; i++) {
            int sum = 0;
            for (int num: mat[i]) sum += num;
            if (sum > 0) cntRows.put(i, sum);
        }
        for (int j = 0; j < mat[0].length; j++) {
            int sum = 0;
            for (int i = 0; i < mat.length; i++) sum += mat[i][j];
            if (sum > 0) cntCols.put(j, sum);
        }
        int ans = 0;
        for (int i = 0; i < mat.length; i++) {
            for (int j = 0; j < mat[0].length; j++) {
                if (mat[i][j] == 1 && cntRows.get(i) == 1 && cntCols.get(j) == 1) ans++;
            }
        }
        return ans;
    }
}