Spiral Matrix II

Given an integer n, generate a square matrix filled with elements from 1 to n2 in spiral order.

For example,
Given n = 3,

You should return the following matrix:

[
 [ 1, 2, 3 ],
 [ 8, 9, 4 ],
 [ 7, 6, 5 ]
]


思路： 控制好边界条件

1. public int[][] generateMatrix(int n) {
2. int[][] res = new int[n][n];
3. int num = 1;
4. // int n2 = Math.pow(n,2);
5. int highrow = n-1;
6. int highcol = n-1;
7. int lowrow = 0;
8. int lowcol = 0;
9. while(true) {
10. if(lowrow>highrow || lowcol > highcol) {
11. break;
12. }
13. if(highrow==lowrow) {
14. for(int i=lowcol;i<=highcol;i++) {
15. res[lowrow][i] = num++;
16. }
17. break;
18. }
19. if(highcol == lowcol) {
20. for(int i=lowrow;i<=highrow;i++) {
21. res[i][lowcol] = num++;
22. }
23. break;
24. }
25. for(int i=lowcol;i<=highcol;i++) {
26. res[lowrow][i] = num++;
27. }
28. for(int i=lowrow+1;i<=highrow;i++) {
29. res[i][highcol] = num++;
30. }
31. for(int i=highcol-1;i>=lowcol;i--) {
32. res[highrow][i] = num++;
33. }
34. for(int i=highrow-1;i>=lowrow+1;i--) {  //注意最后一个边界
35. res[i][lowcol] = num++;
36. }
37. highrow--;
38. highcol--;
39. lowrow++;
40. lowcol++;
41. }
42. return res;
43. }