UVA 10099 The Tourist Guide

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <algorithm>
 4 #include <cstring>
 5 
 6 using namespace std;
 7 const int MAXN=110;
 8 const int MAXM=10100;
 9 const int inf=50000000;
10 struct e{
11     int u,v,w;
12 }edge[MAXM];
13 int n,m;
14 int s,t,num;
15 
16 bool cmp(struct e A,struct e B){
17     if(A.w>B.w)return true;
18     return false;
19 }
20 int pre[MAXN],rank[MAXN];
21 
22 int find(int x){
23     int r=x;
24     while(pre[r]!=-1)
25     r=pre[r];
26     while(x!=r){
27         int q=pre[x];
28         pre[x]=r;
29         x=q;
30     }
31     return r;
32 }
33 
34 bool slove(int mid){
35     for(int i=0;i<m;i++){
36         if(edge[i].w<mid) break;
37         int t1=find(edge[i].u);
38         int t2=find(edge[i].v);
39         if(t1==t2) continue;
40         if(rank[t1]>rank[t2]){
41             pre[t2]=t1;
42         }
43         else if(rank[t2]<rank[t1])
44         pre[t1]=t2;
45         else {
46             rank[t2]++;
47             pre[t1]=t2;
48         }
49     }
50     if(find(s)==find(t))
51     return true;
52     return false;
53 }
54 
55 int main(){
56     int cas=0;
57     int u,v,w;
58     while(scanf("%d%d",&n,&m)!=EOF){
59         if(n==0&&m==0) break;
60         cas++;
61         for(int i=0;i<m;i++){
62             scanf("%d%d%d",&u,&v,&w);
63             edge[i].u=u;edge[i].v=v;
64             edge[i].w=w;
65         }
66         scanf("%d%d%d",&s,&t,&num);
67         sort(edge,edge+m,cmp);
68         int high=inf,low=0;
69         int ans=inf;
70         while(low<=high){
71             int mid=(low+high)/2;
72             memset(pre,-1,sizeof(pre));
73             memset(rank,0,sizeof(rank));
74             if(slove(mid)){
75                 ans=mid; low=mid+1;
76             }
77             else high=mid-1;
78         }
79         int a=num/(ans-1)+(num%(ans-1)>0?1:0);
80         printf("Scenario #%d\n",cas);
81         printf("Minimum Number of Trips = %d\n\n",a);
82     }
83     return 0;
84 }