867. Transpose Matrix

Given a 2D integer array `matrix`, return the transpose of `matrix`.

The transpose of a matrix is the matrix flipped over its main diagonal, switching the matrix's row and column indices.

Example 1:

```Input: matrix = [[1,2,3],[4,5,6],[7,8,9]]
Output: [[1,4,7],[2,5,8],[3,6,9]]
```

Example 2:

```Input: matrix = [[1,2,3],[4,5,6]]
Output: [[1,4],[2,5],[3,6]]
```

Constraints:

• `m == matrix.length`
• `n == matrix[i].length`
• `1 <= m, n <= 1000`
• `1 <= m * n <= 105`
• `-109 <= matrix[i][j] <= 109`

867. Transpose Matrix
``````struct Solution;

impl Solution {
fn transpose(a: Vec<Vec<i32>>) -> Vec<Vec<i32>> {
let n = a.len();
let m = a[0].len();
let mut res: Vec<Vec<i32>> = vec![vec![0; n]; m];
for i in 0..n {
for j in 0..m {
res[j][i] = a[i][j];
}
}
res
}
}

#[test]
fn test() {
let a: Vec<Vec<i32>> = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
.iter()
.map(|x| x.to_vec())
.collect();
let b: Vec<Vec<i32>> = [[1, 4, 7], [2, 5, 8], [3, 6, 9]]
.iter()
.map(|x| x.to_vec())
.collect();
assert_eq!(Solution::transpose(a), b);
let a: Vec<Vec<i32>> = [[1, 2, 3], [4, 5, 6]].iter().map(|x| x.to_vec()).collect();
let b: Vec<Vec<i32>> = [[1, 4], [2, 5], [3, 6]]
.iter()
.map(|x| x.to_vec())
.collect();
assert_eq!(Solution::transpose(a), b);
}
``````