[leetcode] 867. Transpose Matrix

题目：

Given a matrix A, return the transpose of A.

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

Example 1:

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

Example 2:

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

Note:

1. 1 <= A.length <= 1000
2. 1 <= A[0].length <= 1000

代码：

import java.util.Arrays;
class Solution {
    public int[][] transpose(int[][] A) {
        if(A.length == 0) return null;
        int[][] B = new int[A[0].length][A.length];
        for(int i = 0; i < A.length; i++){
            for(int j = 0;j < A[0].length; j++){
                B[j][i] = A[i][j];
            }
        }
        return B;
    }
}