hdu 1875 畅通工程再续

  1 #include<iostream>
  2 #include<cmath>
  3 #include<algorithm>
  4 #include<cstdio>
  5 using namespace std;
  6 #define maxn 300
  7 int par[maxn];
  8 int pos;
  9 int n,cnt;
 10 double len;
 11 struct node
 12 {
 13     int x;
 14     int y;
 15     double w;//!!!可以不开方
 16 };
 17 node e[maxn * (maxn - 1) / 2];
 18 int cmp(const node &a , const node &b)
 19 {
 20     return a.w < b.w;
 21 };
 22 struct p
 23 {
 24     int x;
 25     int y;
 26 }po[maxn];
 27 void init()
 28 {
 29     for(int i = 1; i <= n+5; i++)
 30         par[i] = i;
 31     pos = 0;
 32     len = 0.0;
 33     cnt = 0;
 34 }
 35 int Find(int x)
 36 {
 37     int k,j,r;
 38     r = x;
 39     while(par[r] != r)
 40         r = par[r];
 41     k = x;
 42     while(k != r)
 43     {
 44         j = par[k];
 45         par[k] = r;
 46         k = j;
 47     }
 48     return r;
 49 }
 50 int Merge(int x,int y)
 51 {
 52     int a = Find(x);
 53     int b = Find(y);
 54     if(a != b)
 55     {
 56         par[a] = par[b];
 57         return 1;
 58     }
 59     return 0;
 60 }
 61 void input()
 62 {
 63     int u,v;
 64     for(int i = 1; i <= n; i++)
 65         scanf("%d%d",&po[i].x,&po[i].y);
 66 }
 67 
 68 void make()
 69 {
 70     double dist;
 71     for(int i = 1; i <= n; i++)
 72     {
 73         for(int j = i + 1; j <= n; j++)
 74         {
 75             dist = (po[i].x - po[j].x) * (po[i].x - po[j].x) + (po[i].y - po[j].y) * (po[i].y - po[j].y);
 76             if(dist >= 100 && dist <= 1000000)
 77             {
 78                 e[pos].x = i;
 79                 e[pos].y = j;
 80                 e[pos].w = sqrt(dist);
 81                 pos++;
 82             }
 83         }
 84     }
 85     sort(e,e+pos,cmp);
 86     for(int i = 0; i < pos; i++)
 87     {
 88         if(Merge(e[i].x,e[i].y))
 89         {
 90             Merge(e[i].x,e[i].y);
 91             len += e[i].w;
 92             cnt++;
 93         }
 94     }
 95 }
 96 int main()
 97 {
 98     freopen("input.txt","r",stdin);
 99     int t;
100     scanf("%d",&t);
101     while(t--)
102     {
103         scanf("%d",&n);
104         init();
105         input();
106         make();
107         if(cnt < n - 1) printf("oh!\n");
108         else printf("%.1lf\n",len * 100);
109     }
110 
111     return 0;
112 }