POJ 1861 Network

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <cstring>
 4 #include <cmath>
 5 #include <algorithm>
 6 #include <climits>
 7 #include <vector>
 8 #include <queue>
 9 #include <cstdlib>
10 #include <string>
11 #include <set>
12 #include <stack>
13 #define LL long long
14 #define pii pair<int,int>
15 #define INF 0x3f3f3f3f
16 using namespace std;
17 const int maxn = 20000;
18 struct arc{
19     int u,v,w;
20     bool operator<(const arc &y) const {
21         return w < y.w;
22     }
23 };
24 arc e[maxn];
25 int n,m,uf[maxn],ans[maxn],tot;;
26 int Find(int x){
27     if(x != uf[x]) uf[x] = Find(uf[x]);
28     return uf[x];
29 }
30 int kruskal(){
31     for(int i = 0; i < 1500; ++i) uf[i] = i;
32     int maxw = tot = 0;
33     for(int i = 0; i < m; ++i){
34         int tx = Find(e[i].u);
35         int ty = Find(e[i].v);
36         if(tx != ty){
37             uf[tx] = ty;
38             ans[tot++] = i;
39             maxw = max(maxw,e[i].w);
40         }
41     }
42     return maxw;
43 }
44 
45 int main() {
46     while(~scanf("%d %d",&n,&m)){
47         for(int i = 0; i < m; ++i)
48             scanf("%d %d %d",&e[i].u,&e[i].v,&e[i].w);
49         sort(e,e+m);
50         printf("%d\n%d\n",kruskal(),tot);
51         for(int i = 0; i < tot; ++i)
52             printf("%d %d\n",e[ans[i]].u,e[ans[i]].v);
53     }
54     return 0;
55 }