2352. Equal Row and Column Pairs

QUESTION:

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] <= 105

EXPLANATION:

模拟出过程即可. 中间colum的是需要重复计算的. 可以提前算出来. 然后再用grid和colum进行比对即可.

SOLUTION:

class Solution {
    func equalPairs(_ grid: [[Int]]) -> Int {
        var colum: [[Int]] = []
        for i in 0...grid.count-1 {
            var tmpArr: [Int] = []
            for j in 0...grid.count-1 {
                tmpArr.append(grid[j][i])
            }
            colum.append(tmpArr)
        }
        var result = 0
        for gr in grid {
            for co in colum {
                if gr == co {
                    result += 1
                }
            }
        }
        return result
    }
}
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