Equal Row and Column Pairs — LeetCode 2352 Python Solution

The problem

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

Input

grid = [[3,2,1],[1,7,6],[2,7,7]]

Output

1

Explanation

There is 1 equal row and column pair:

Python solution

class Solution:
    def equalPairs(self, grid: List[List[int]]) -> int:
        n = len(grid)
        ans = 0
        for i in range(n):
            for j in range(n):
                ans += all(grid[i][k] == grid[k][j] for k in range(n))
        return ans

Complexity

Pattern: Matrix and Grid

Treat a 2-D grid as a graph whose neighbours are the four adjacent cells. LeetCode 2352. Equal Row and Column Pairs is filed here because LeetCode tags it Matrix, which is the vocabulary this hub collects.

The matrix and grid guide has the Python template for the pattern and the 216 LeetCode problems that use it.

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