2352. Equal Row and Column Pairs
Medium
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].length1 <= n <= 2001 <= grid[i][j] <= 105
先建立 map 來儲存 相異 row 出現的次數，再與 column 進行比較和答案的加總。
func equalPairs(grid [][]int) int {
m := make(map[string]int)
res := 0
for i:=0; i<len(grid); i++ {
s := ""
for j:=0; j<len(grid[0]); j++ {
s += strconv.Itoa(grid[i][j])
s += "/"
}
m[s]++
}
for i:=0; i<len(grid[0]); i++ {
s := ""
for j:=0; j<len(grid); j++ {
s += strconv.Itoa(grid[j][i])
s += "/"
}
if m[s]!=0 {
res += m[s]
}
}
return res
}