题目描述
You are given an n x n 2D matrix representing an image.
Rotate the image by 90 degrees (clockwise).
Follow up:
Could you do this in-place?
代码
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
|
public class Solution {
1 2 3 1 4 7 7 4 1
4 5 6 => 2 5 8 => 8 5 2
7 8 9 3 6 9 9 6 3
*/
public void rotate(int[][] matrix) {
if(matrix == null || matrix.length == 0 || matrix[0].length == 0) return;
int length = matrix.length;
for(int i = 0; i < length; i++){
for(int j = i+1; j < length; j++){
int temp = matrix[i][j];
matrix[i][j] = matrix[j][i];
matrix[j][i] = temp;
}
}
for(int i = 0; i < length; i++){
for(int j = 0; j < length/2; j++){
int temp = matrix[i][j];
matrix[i][j] = matrix[i][length-j-1];
matrix[i][length-j-1] = temp;
}
}
}
1 2 3 1 4 7 3 6 9
4 5 6 => 2 5 8 => 2 5 8
7 8 9 3 6 9 1 4 7
*/
public void rotate2(int[][] matrix){
if(matrix == null || matrix.length == 0 || matrix[0].length == 0) return;
int length = matrix.length;
for(int i = 0; i < length; i++){
for(int j = i+1; j < length; j++){
int temp = matrix[i][j];
matrix[i][j] = matrix[j][i];
matrix[j][i] = temp;
}
}
for(int i = 0; i < length/2; i++){
for(int j = 0; j < length; j++){
int temp = matrix[i][j];
matrix[i][j] = matrix[length-i-1][j];
matrix[length-i-1][j] = temp;
}
}
}
}
|
近期评论