Leetcodes Solutions 48 Rotate Image
匯總
雪之下雪乃：leetcode解題總匯
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]]
思路1：有一種通用的方法：首先上下把行的次序顛倒，在按對角線交換
/* * clockwise rotate * first reverse up to down, then swap the symmetry * 1 2 3 7 8 9 7 4 1 * 4 5 6 => 4 5 6 => 8 5 2 * 7 8 9 1 2 3 9 6 3*/
class Solution {public: void rotate(vector<vector<int>>& matrix){ reverse(matrix.begin(), matrix.end()); for(int i = 0; i < matrix.size(); i++){ for(int j = i + 1; j < matrix[i].size(); ++j) swap(matrix[i][j], matrix[j][i]); } }};
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