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  • #LeetCode# 48. Rotate Image

    https://leetcode.com/problems/rotate-image/

    You are given an n x n 2D matrix representing an image.

    Rotate the image by 90 degrees (clockwise).

    Note:

    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:

    Given input matrix = 
    [
      [1,2,3],
      [4,5,6],
      [7,8,9]
    ],
    
    rotate the input matrix in-place such that it becomes:
    [
      [7,4,1],
      [8,5,2],
      [9,6,3]
    ]
    

    Example 2:

    Given input matrix =
    [
      [ 5, 1, 9,11],
      [ 2, 4, 8,10],
      [13, 3, 6, 7],
      [15,14,12,16]
    ], 
    
    rotate the input matrix in-place such that it becomes:
    [
      [15,13, 2, 5],
      [14, 3, 4, 1],
      [12, 6, 8, 9],
      [16, 7,10,11]
    ]

    代码:

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

     

    和 HDU 2135 类似:https://www.cnblogs.com/zlrrrr/p/9709672.html

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  • 原文地址:https://www.cnblogs.com/zlrrrr/p/9984020.html
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