力扣每日一题2022-09-04简单题：二进制矩阵中的特殊位置

---

题目描述

二进制矩阵中的特殊位置

---

思路

模拟

根据题意，模拟即可。

Python实现

class Solution:
    def numSpecial(self, mat: List[List[int]]) -> int:
        r_sum  = [sum(row) for row in mat]
        c_sum = [sum(col) for col in zip(*mat)]
        ans = 0
        for i, row in enumerate(mat):
            for j, x in enumerate(row):
                if x == 1 and r_sum[i] == 1 and c_sum[j] == 1:
                    ans += 1
        return ans

Java实现

class Solution {
    public int numSpecial(int[][] mat) {
        int m = mat.length, n = mat[0].length;
        int[] r_sum = new int[m];
        int[] c_sum = new int[n];
        for (int i = 0; i < m; i++) {
            for (int j = 0; j < n; j++) {
                r_sum[i] += mat[i][j];
                c_sum[j] += mat[i][j];
            }
        }
        int ans = 0;
        for (int i = 0; i < m; i++) {
            for (int j = 0; j < n; j++) {
                if (mat[i][j] == 1 && r_sum[i] == 1 && c_sum[j] == 1) {
                    ans++;
                }
            }
        }
        return ans;
    }
}

C++实现

class Solution {
public:
    int numSpecial(vector<vector<int>>& mat) {
        int m = mat.size(), n = mat[0].size();
        vector<int> r_sum(m);
        vector<int> c_sum(n);
        for (int i = 0; i < m; i++) {
            for (int j = 0; j < n; j++) {
                r_sum[i] += mat[i][j];
                c_sum[j] += mat[i][j];
            }
        }
        int ans = 0;
        for (int i = 0; i < m; i++) {
            for (int j = 0; j < n; j++) {
                if (mat[i][j] == 1 && r_sum[i] == 1 && c_sum[j] == 1) {
                    ans++;
                }
            }
        }
        return ans;
    }
};