# leetcode 2352. Equal Row and Column Pairs（python）

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### 描述

Given a 0-indexed n x n integer matrix grid, return the number of pairs (Ri, Cj) such that row Ri and column Cj are equal.

A row and column pair is considered equal if they contain the same elements in the same order (i.e. an equal array).

Example 1:

Input: grid = [[3,2,1],[1,7,6],[2,7,7]]
Output: 1
Explanation: There is 1 equal row and column pair:
- (Row 2, Column 1): [2,7,7]

Example 2:

Input: grid = [[3,1,2,2],[1,4,4,5],[2,4,2,2],[2,4,2,2]]
Output: 3
Explanation: There are 3 equal row and column pairs:
- (Row 0, Column 0): [3,1,2,2]
- (Row 2, Column 2): [2,4,2,2]
- (Row 3, Column 2): [2,4,2,2]

Note:

n == grid.length == grid[i].length
1 <= n <= 200
1 <= grid[i][j] <= 10^5

### 解答

class Solution:
def equalPairs(self, grid: List[List[int]]) -> int:
counter = collections.Counter(tuple(r) for r in grid)
return sum(counter[c] for c in zip(*grid))

### 运行结果

69 / 69 test cases passed.
Status: Accepted
Runtime: 674 ms
Memory Usage: 18.1 MB

### 原题链接

https://leetcode.com/contest/weekly-contest-303/problems/equal-row-and-column-pairs/