ZOJ 2048 Highways

kruskal实现
  1 #include<iostream>
  2 #include<cmath>
  3 #include<algorithm>
  4 #include<cstdio>
  5 using namespace std;
  6 #define maxn 760
  7 int par[maxn];
  8 int pos;
  9 int n,m;
 10 struct node
 11 {
 12     int x;
 13     int y;
 14     double w;//!可以不开方比较
 15 };
 16 node e[maxn * (maxn - 1) / 2];
 17 int cmp(const node &a , const node &b)
 18 {
 19     return a.w < b.w;
 20 };
 21 struct p
 22 {
 23     int x;
 24     int y;
 25 }po[maxn];
 26 void init()
 27 {
 28     for(int i = 1; i <= n+5; i++)
 29         par[i] = i;
 30     pos = 0;
 31 }
 32 int Find(int x)
 33 {
 34     int k,j,r;
 35     r = x;
 36     while(par[r] != r)
 37         r = par[r];
 38     k = x;
 39     while(k != r)
 40     {
 41         j = par[k];
 42         par[k] = r;
 43         k = j;
 44     }
 45     return r;
 46 }
 47 void Merge(int x,int y)
 48 {
 49     int a = Find(x);
 50     int b = Find(y);
 51     if(a != b)
 52     {
 53         par[a] = par[b];
 54     }
 55 }
 56 void input()
 57 {
 58     int u,v;
 59     for(int i = 1; i <= n; i++)
 60         cin>>po[i].x>>po[i].y;
 61     cin>>m;
 62     while(m--)
 63     {
 64         cin>>u>>v;
 65         Merge(u,v);
 66     }
 67 }
 68 
 69 void make()
 70 {
 71     for(int i = 1; i <= n; i++)
 72     {
 73         for(int j = i + 1; j <= n; j++)
 74         {
 75             if(Find(i) != Find(j))
 76             {
 77                 e[pos].x = i;
 78                 e[pos].y = j;
 79                 e[pos].w = (po[i].x - po[j].x) * (po[i].x - po[j].x) + (po[i].y - po[j].y) * (po[i].y - po[j].y);
 80                 pos++;
 81             }
 82         }
 83     }
 84     sort(e,e+pos,cmp);
 85     for(int i = 0; i < pos; i++)
 86     {
 87         if(Find(e[i].x) != Find(e[i].y))
 88         {
 89             Merge(e[i].x,e[i].y);
 90             cout<<e[i].x<<" "<<e[i].y<<endl;
 91         }
 92     }
 93 }
 94 int main()
 95 {
 96     freopen("input.txt","r",stdin);
 97     int t;
 98     cin>>t;
 99     while(t--)
100     {
101         cin>>n;
102         init();
103         input();
104         make();
105         if(t!=0)cout<<endl; //There is a blank line between output blocks.except the last one
106     }
107 
108     return 0;
109 }