Equal Row and Column Pairs
<p>Given a <strong>0-indexed</strong> <code>n x n</code> integer matrix <code>grid</code>, <em>return the number of pairs </em><code>(r<sub>i</sub>, c<sub>j</sub>)</code><em> such that row </em><code>r<sub>i</sub></code><em> and column </em><code>c<sub>j</sub></code><em> are equal</em>.</p>

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

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://fastly.jsdelivr.net/gh/doocs/leetcode@main/solution/2300-2399/2352.Equal%20Row%20and%20Column%20Pairs/images/ex1.jpg" style="width: 150px; height: 153px;" />
<pre>
<strong>Input:</strong> grid = [[3,2,1],[1,7,6],[2,7,7]]
<strong>Output:</strong> 1
<strong>Explanation:</strong> There is 1 equal row and column pair:
- (Row 2, Column 1): [2,7,7]
</pre>

<p><strong class="example">Example 2:</strong></p>
<img alt="" src="https://fastly.jsdelivr.net/gh/doocs/leetcode@main/solution/2300-2399/2352.Equal%20Row%20and%20Column%20Pairs/images/ex2.jpg" style="width: 200px; height: 209px;" />
<pre>
<strong>Input:</strong> grid = [[3,1,2,2],[1,4,4,5],[2,4,2,2],[2,4,2,2]]
<strong>Output:</strong> 3
<strong>Explanation:</strong> 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]
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>n == grid.length == grid[i].length</code></li>
	<li><code>1 &lt;= n &lt;= 200</code></li>
	<li><code>1 &lt;= grid[i][j] &lt;= 10<sup>5</sup></code></li>
</ul>
Array; Hash Table; Matrix; Simulation
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
