2352.相等行列对

链接：2352.相等行列对
难度：Medium
标签：数组、哈希表、矩阵、模拟
简介：给你一个下标从 0 开始、大小为 n x n 的整数矩阵 grid ，返回满足 Ri 行和 Cj 列相等的行列对 (Ri, Cj) 的数目。

题解 1 - cpp

• 编辑时间：2023-06-06
• 执行用时：224ms
• 内存消耗：43MB
• 编程语言：cpp
• 解法介绍：哈希存储。

class Solution {
public:
    int equalPairs(vector<vector<int>>& grid) {
        unordered_map<string, int> rows;
        int res = 0, n = grid.size();
        for (int i = 0; i < n; i++) {
            string key = "";
            for (int j = 0; j < n; j++) key += to_string(grid[i][j]) + ",";
            rows[key]++;
        }
        for (int j = 0; j < n; j++) {
            string key = "";
            for (int i = 0; i < n; i++) key += to_string(grid[i][j]) + ",";
            res += rows[key];
        }
        return res;
    }
};

题解 2 - python

• 编辑时间：2023-06-06
• 执行用时：212ms
• 内存消耗：20.6MB
• 编程语言：python
• 解法介绍：同上。

class Solution:
    def equalPairs(self, grid: List[List[int]]) -> int:
        rows = Counter()
        res = 0
        n = len(grid)
        for i in range(n):
            key = ""
            for j in range(n):
                key += str(grid[i][j]) + ","
            rows[key] += 1
        for j in range(n):
            key = ""
            for i in range(n):
                key += str(grid[i][j]) + ","
            res += rows[key]
        return res

题解 3 - rust

• 编辑时间：2023-06-06
• 执行用时：44ms
• 内存消耗：3MB
• 编程语言：rust
• 解法介绍：同上。

impl Solution {
pub fn equal_pairs(grid: Vec<Vec<i32>>) -> i32 {
    let mut rows = std::collections::HashMap::<String, i32>::new();
    let mut res = 0;
    let n = grid.len();
    for i in 0..n {
        let mut key = String::new();
        for j in 0..n {
            key.push_str(&format!("{}", grid[i][j]));
            key.push(',');
        }
        *rows.entry(key).or_insert(0) += 1;
    }
    for j in 0..n {
        let mut key = String::new();
        for i in 0..n {
            key.push_str(&format!("{}", grid[i][j]));
            key.push(',');
        }
        res += *rows.entry(key).or_insert(0);
    }
    res
}
}