題目

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:

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

Example 2:

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

Constraints:

$$ \begin{array}{l} m == matrix.length \\ n == matrix[i].length \\ 1 <= m, n <= 1000 \\ 1 <= m * n <= 105 \\ -109 <= matrix[i][j] <= 109 \end{array} $$

我的思路

假設現在已經給了 N * M 的 Array ，那就建立一個新的 2D Array M * N。

Loop 一遍整個 Array，將 要返回的Array[m][n] 設定成 Input Array[n][m];

程式碼

 1class Solution {
 2    public int[][] transpose(int[][] matrix) {
 3        int[][] result = new int[matrix[0].length][matrix.length];
 4        
 5        for(int n = 0; n < matrix.length; n++) {
 6            for(int m = 0; m < matrix[0].length; m++) {
 7                result[m][n] = matrix[n][m];
 8            }
 9        }
10        
11        return result;
12    }
13}