*LeetCode-Rotate Image

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cc书上的方法就是每一层分成四个旋转 index非常难想

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

第二种方法很巧妙就是先上下reverse 然后对角线swap

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

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