poj1696/hlg1318 蛋疼的蚂蚁

 1 #include <iostream>
 2 #include <cstring>
 3 #include <cstdio>
 4 #include <algorithm>
 5 using namespace std;
 6 
 7 const int maxn = 55;
 8 struct point
 9 {
10     int id;
11     int x;
12     int y;
13 }poin[maxn];
14 
15 bool cmp(point p1, point p2){
16     if(p1.y != p2.y)
17         return p1.y < p2.y;
18     return p1.x < p2.x;
19 }
20 
21 int cross(point p0, point p1, point p2)
22 {
23     return (p1.x - p0.x)*(p2.y - p0.y) - (p2.x - p0.x)*(p1.y - p0.y);
24 }
25 
26 int Distance(point p1, point p2)
27 {
28     return (p2.x - p1.x)*(p2.x - p1.x) + (p2.y - p1.y)*(p2.y - p1.y);
29 }
30 int pos;
31 
32 bool Polar_cmp(point p1, point p2)
33 {
34     int tmp = cross(poin[pos], p1, p2);
35     if(tmp)
36         return tmp > 0;
37     return Distance(poin[pos], p1) <= Distance(poin[pos], p2);
38 }
39 
40 int main()
41 {
42     int t, n;
43     scanf("%d",&t);
44     while(t--){
45         scanf("%d", &n);
46         for(int i = 0; i < n; i++)
47             scanf("%d %d %d",&poin[i].id, &poin[i].x, &poin[i].y);
48         int ans[maxn];
49         int k = 0;
50         sort(poin, poin + n, cmp);
51         pos = 0;
52         int cnt = n - 1;
53         for(int i = 1; i <= cnt; i++)
54         {
55             sort(poin + i, poin + n, Polar_cmp);
56             //printf("*%d ",poin[i].id);
57             pos++;
58         }
59         printf("%d",n);
60         for(int i = 0; i < n; i++)
61             printf(" %d",poin[i].id);
62         puts("");
63     }
64     return 0;
65 }