Question

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

Difficulty:Easy

Category:Array

Analyze

How can we solve this problem in-place.

  • In-Place Inverse Perfect Shuffle

Solution

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, 0));
    transpose(A, res, m, n);
    return res;
  }

  void transpose(vector<vector<int>>& a, vector<vector<int>>& b, int rows, int cols) {
    for (int i = 0; i < rows; i++) {
      for (int j = 0; j < cols; j++) {
        b[j][i] = a[i][j];
      }
    }
    return;
  }
};
By guozetang            Updated: 2020-09-19 13:02:30

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