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);
}