2352.equal-row-and-column-pairs.py

#
# @lc app=leetcode id=2352 lang=python3
#
# [2352] Equal Row and Column Pairs
#
# https://leetcode.com/problems/equal-row-and-column-pairs/description/
#
# algorithms
# Medium (70.32%)
# Likes:    2327
# Dislikes: 173
# Total Accepted:    299.8K
# Total Submissions: 426.4K
# Testcase Example:  '[[3,2,1],[1,7,6],[2,7,7]]'
#
# 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]
#
#
#
# Constraints:
#
#
# n == grid.length == grid[i].length
# 1 <= n <= 200
# 1 <= grid[i][j] <= 10^5
#
#
#

# @lc code=start
from collections import Counter
from typing import List


class Solution:
    def equalPairs(self, grid: List[List[int]]) -> int:
        row_count = Counter(tuple(row) for row in grid)
        col_count = Counter(tuple(col) for col in zip(*grid))

        return sum(row_count[key] * col_count[key] for key in row_count)


# @lc code=end