题解 | #顺时针旋转矩阵#

public class Solution {
    //基本要求：增加空间复杂度
    public int[][] rotateMatrix_base(int[][] mat, int n) {
        
        int[][] rotate = new int[n][n];
        
        for(int i=0; i<n; i++){
            for(int j=0; j<n; j++){
                rotate[j][n-1-i] = mat[i][j];
            }
        }
        return rotate;
    }
    //进阶：直接在原矩阵上修改
    public int[][] rotateMatrix(int[][] mat, int n) {
        //对角翻转
        for(int i=0; i<n; i++){
            for(int j=0; j<i; j++){
                int tmp = mat[i][j];
                mat[i][j] = mat[j][i];
                mat[j][i] = tmp;
            }
        }
        //左右翻转
        for(int i=0; i<n; i++){
            for(int j=0; j<n/2; j++){
                int tmp = mat[i][j];
                mat[i][j] = mat[i][n-1-j];
                mat[i][n-1-j] = tmp;
            }
        }
        return mat;
    }
}