leetcode-867-easy

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

思路一：最关键的是 ans[j][i] = matrix[i][j]

    public int[][] transpose(int[][] matrix) {
        int m = matrix.length;
        int n = matrix[0].length;

        int[][] ans = new int[n][m];

        for (int i = 0; i < m; i++) {
            for (int j = 0; j < n; j++) {
                ans[j][i] = matrix[i][j];
            }
        }

        return ans;
    }