Leetcode 867. Transpose Matrix, Java解法

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

Approach #1 Brute Force, Copy Directly 我的解法

class Solution {
    public int[][] transpose(int[][] A) {
    int row = A.length;
    int col = A[0].length;
    int[][] ans = new int[col][row];
    for(int i=0;i<col;++i){
        for(int j=0;j<row;++j){
            ans[i][j] = A[j][i];
        }
    }
    return ans;
    }
}

Complexity Analysis

• Time Complexity: O(R * C), where R and C are the number of rows and columns in the given matrix A.

• Space Complexity: O(R * C), the space used by the answer. 

Tips:

需要注意这个矩阵不一定是方的，审题要注意。