LeetCode刷题：867.Transpose Matrix

867. Transpose Matrix

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

   解题思路：

   A为m * n的矩阵，所以A的转置为n * m的矩阵，故先创建n * m的矩阵result，通过遍历令result[j][i] = A[i][j],最后返回result

   解答：

   class Solution {
   public:
   vector<vector<int>> transpose(vector<vector<int>>& A) {
       int m = A.size();
       int n = A[0].size();
       /*
        * A为m * n的矩阵，则A的转置为n * m的矩阵
        * 所以定义result为n * m的矩阵
        */
       vector<vector<int>> result(n);
       for(int i = 0; i < n; ++i)
           result[i].resize(m);
       for(int i = 0; i < m; ++i)
       {  
           for(int j = 0; j < n; ++j)
           {
               result[j][i] = A[i][j];
           }
       }
       return result;
   }
   };