48. Rotate Image
給定一個 n x n 的二維矩陣表示一個圖像，將該圖像旋轉 90 度（順時針）。
你必須就地旋轉圖像，這意味著你必須直接修改輸入的二維矩陣。不要分配另一個二維矩陣並進行旋轉。
範例 1：
輸入：matrix = [[1,2,3],[4,5,6],[7,8,9]] 輸出：[[7,4,1],[8,5,2],[9,6,3]]
Python
from typing import List
class Solution:
def rotate(self, matrix: List[List[int]]) -> None:
"""
Do not return anything, modify matrix in-place instead.
"""
n = len(matrix)
# Step 1: Transpose the matrix
for i in range(n):
for j in range(i, n):
matrix[i][j], matrix[j][i] = matrix[j][i], matrix[i][j]
# Step 2: Reverse each row
for i in range(n):
matrix[i].reverse()
16.66MB, 39ms
C++
#include <vector>
using namespace std;
class Solution {
public:
void rotate(vector<vector<int>>& matrix) {
int n = matrix.size();
// Step 1: Transpose the matrix
for (int i = 0; i < n; ++i) {
for (int j = i; j < n; ++j) {
swap(matrix[i][j], matrix[j][i]);
}
}
// Step 2: Reverse each row
for (int i = 0; i < n; ++i) {
reverse(matrix[i].begin(), matrix[i].end());
}
}
};
8.64MB, 0ms
Javascript
/**
* @param {number[][]} matrix
* @return {void} Do not return anything, modify matrix in-place instead.
*/
var rotate = function(matrix) {
const n = matrix.length;
// Step 1: Transpose the matrix
for (let i = 0; i < n; i++) {
for (let j = i; j < n; j++) {
[matrix[i][j], matrix[j][i]] = [matrix[j][i], matrix[i][j]];
}
}
// Step 2: Reverse each row
for (let i = 0; i < n; i++) {
matrix[i].reverse();
}
};
50.62MB, 55ms
