蛇形矩陣

題目參考<算法競賽入門經典>第二版第三章 3.1

 1 #include <stdio.h>
 2 #include <string.h>
 3 
 4 #define N 20
 5 int a[N][N];
 6 int main(int argc, char **argv){
 7     int n;
 8     while(scanf("%d",&n)!=EOF){
 9     memset(a, 0, sizeof(a));
10     int tol = 1;
11     int x, y;
12     x = -1;
13     y = n;
14     while(tol<=n*n){
15         x++;
16         y--;
17         while( x < n && a[x][y] == 0){
18         a[x++][y] = tol++;
19         }// x =  n  y = n-1
20         x--;
21         y--;
22         while(y >= 0 && a[x][y] == 0){
23         a[x][y--] = tol++;
24         }
25         x--;
26         y++;
27         while(x >= 0 && a[x][y] == 0){
28         a[x--][y] = tol++;
29         }
30         x++;
31         y++;
32         while( y < n && a[x][y] == 0){
33         a[x][y++] = tol++;
34         }
35     }
36     for(int i=0; i<n;i++){
37         for(int j=0;j<n;j++){
38         printf("%3d ",a[i][j]);
39         }
40         printf("\n");
41     }
42     }
43     return 0;
44 }