48.Rotate image

public class Main { //一开始我也想了很多方法 用另外一个矩阵帮忙保存 结果是错的
    public void rotate(int[][] matrix) {
        int n = matrix.length;
        int top = 0, left = 0, right = n - 1, bot = n - 1;
        int temp;
        while (n>1) {//通过网上的视频点通自己的思路 ，因为我一直都在研究里面的规律 导致解法错误 
            for (int i = 0; i < n - 1; i++) {
                temp = matrix[top ][left+i];
                matrix[top][left+i] = matrix[bot - i][left];
                matrix[bot - i][left] = matrix[bot][right - i];
                matrix[bot][right - i] = matrix[top + i][right];
                matrix[top +i][right] = temp;
            }
            n = n - 2;
            top++;
            left++;
            right--;
            bot--;
        }
    }
}

然后各种思路是对的 答案里面老是有数值重复 然后去找视频教程 附上教程
https://www.bilibili.com/video/av10479026
下面我分析其他人的解法

class Solution {
    public void rotate(int[][] matrix) {
        if(matrix.length == 1) {//如果是一个数 就返回出来
            return;
        }
        rotateMatrix(0, matrix.length, matrix);//否则调用函数
    }
    private void rotateMatrix(int i, int len, int[][] matrix) {
    if(len <= 1) { //递归结束
        return;
    }else if(i == len - 1) { //进入下一层 
        len -= 2;//还没处理的层数
        i = 0;//出口条件
        rotateMatrix(i, len, matrix);
        }
else {
        int layer = (matrix.length - len) / 2;  //计算当前第几层
        //交换4个元素
            int a1 = matrix[layer][layer + i];
        int a2 = matrix[layer + i][matrix.length - layer - 1];
        int a3 = matrix[matrix.length - layer - 1][matrix.length - layer - i - 1];
            int a4 = matrix[matrix.length - layer - i - 1][layer];
        matrix[layer + i][matrix.length - layer - 1] = a1;
        matrix[matrix.length - layer -1][matrix.length - layer - i - 1] = a2;
        matrix[matrix.length - layer -i - 1][layer] = a3;
        matrix[layer][layer+ i] = a4;//四个值做一个旋转 用了八条语句有些笨重 可以用一个temp值记录
            rotateMatrix(i + 1, len, matrix);//同一层进行转换
        }
    }
}

public void rotate(int[][] matrix) {
    if (matrix == null || matrix.length <= 1) {
        return;
    }
    int n = matrix.length;
    for (int i = 0; i < n; i++) {//通过对角线进行交换
        for (int j = i; j < n; j++) {
            int temp = matrix[i][j];
            matrix[i][j] = matrix[j][i];
            matrix[j][i] = temp;
        }
    }
    for (int i = 0; i < n; i++) {//同一行 中线对称 进行交换
        int head = 0;
        int tail = n - 1;
        while (head < tail) {
            int temp = matrix[i][head];
            matrix[i][head] = matrix[i][tail];
            matrix[i][tail] = temp;
            head++;
            tail--;
        }
    }
}

For example, if the matrix is:
1 2 3
4 5 6
7 8 9
then after the first for loop, it becomes: 
1 4 7
2 5 8
3 6 9
then after the second for loop, it becomes: 
7 4 1
8 5 2
9 6 3