LeetCode-48. Rotate Image [C++][Java]

LeetCode-48. Rotate Imagehttps://leetcode.com/problems/rotate-image/

You are given an n x n 2D matrix representing an image, rotate the image by 90 degrees (clockwise).

You have to rotate the image in-place, which means you have to modify the input 2D matrix directly. DO NOT allocate another 2D matrix and do the rotation.

Example 1:

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

Example 2:

Input: matrix = [[5,1,9,11],[2,4,8,10],[13,3,6,7],[15,14,12,16]]
Output: [[15,13,2,5],[14,3,4,1],[12,6,8,9],[16,7,10,11]]

Constraints:

• n == matrix.length == matrix[i].length
• 1 <= n <= 20
• -1000 <= matrix[i][j] <= 1000

【C++】

class Solution {
public:
    void rotate(vector>& matrix) {
        int temp = 0, n = matrix.size()-1;
        for (int i = 0; i <= n / 2; ++i) {
            for (int j = i; j < n - i; ++j) {
                temp = matrix[j][n-i];
                matrix[j][n-i] = matrix[i][j];
                matrix[i][j] = matrix[n-j][i];
                matrix[n-j][i] = matrix[n-i][n-j];
                matrix[n-i][n-j] = temp;
            }
        }
    }
};

【Java】

class Solution {
    public void rotate(int[][] matrix) {
        int temp = 0, n = matrix.length-1;
        for (int i = 0; i <= n / 2; ++i) {
            for (int j = i; j < n - i; ++j) {
                temp = matrix[j][n-i];
                matrix[j][n-i] = matrix[i][j];
                matrix[i][j] = matrix[n-j][i];
                matrix[n-j][i] = matrix[n-i][n-j];
                matrix[n-i][n-j] = temp;
            }
        }
    }
}