Transpose Matrix 转置矩阵

/**
 * @brief The Solution class
 * 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 <= A.length <= 1000
1 <= A[0].length <= 1000
*/

class Solution{
public:
    vector<vector<int>> transpose(vector<vector<int>>& A){
        int m = A.size(),n=A[0].size();
        vector<vector<int>> res(n,vector<int>(m));

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