顺时针旋转矩阵

  public int[][] rotateMatrix(int[][] mat, int n) {
        // write code here

        int[][] nums=new int[n][n];

        if(n==0||mat==null) return nums;
        
        for (int i=0;i<n;i++){
            for (int j=0;j<n;j++){
                nums[i][n-j-1]=mat[j][i];
            }
        }

        return nums;
    }