Vijos1901 学姐的钱包

  1 /*by SilverN*/
  2 #include<algorithm>
  3 #include<iostream>
  4 #include<cstring>
  5 #include<cstdio>
  6 #include<cmath>
  7 #include<vector>
  8 #include<queue>
  9 #include<map>
 10 #define LL long long
 11 using namespace std;
 12 const int mxn=400010;
 13 int read(){
 14     int x=0,f=1;char ch=getchar();
 15     while(ch<‘0‘ || ch>‘9‘){if(ch==‘-‘)f=-1;ch=getchar();}
 16     while(ch>=‘0‘ && ch<=‘9‘){x=x*10+ch-‘0‘;ch=getchar();}
 17     return x*f;
 18 }
 19 struct edge{
 20     int v,nxt,dis;
 21 }e[mxn<<2];
 22 int hd[mxn],mct=0;
 23 void add_edge(int u,int v,int dis){
 24     e[++mct].v=v;e[mct].dis=dis;e[mct].nxt=hd[u];hd[u]=mct;
 25     return;
 26 }
 27 //
 28 struct node{
 29     int val,id;
 30 }a[mxn];
 31 int cmp(const node a,const node b){
 32     return a.val<b.val;
 33 }
 34 map<int,int>mp;
 35 int id=0;
 36 int T;
 37 int n,m;
 38 int u[mxn],v[mxn],d[mxn];
 39 queue<int>q;
 40 bool inq[mxn];
 41 LL dis[mxn];LL INF;
 42 void SPFA(int st){
 43     memset(dis,0x3f,sizeof dis);
 44     INF=dis[0];
 45     while(!q.empty()) q.pop();
 46     q.push(st);
 47     inq[st]=1;
 48     dis[st]=0;
 49     while(!q.empty()){
 50         int u=q.front();q.pop();
 51         for(int i=hd[u];i;i=e[i].nxt){
 52             int v=e[i].v;
 53             if(dis[v]>dis[u]+e[i].dis){
 54                 dis[v]=dis[u]+e[i].dis;
 55                 if(!inq[v]){
 56                     inq[v]=1;
 57                     q.push(v);
 58                 }
 59             }
 60         }
 61         inq[u]=0;
 62     }
 63     return;
 64 }
 65 void init(){
 66     memset(e,0,sizeof e);
 67     memset(hd,0,sizeof hd);
 68     memset(inq,0,sizeof inq);
 69     mct=id=0;
 70     mp.clear();
 71     return;
 72 }
 73 
 74 int main(){
 75     freopen("10.in","r",stdin);
 76     T=read();
 77     int i,j;
 78     int cas=0;
 79     while(T--){
 80         init();
 81         n=read();m=read();
 82         mp[m]=++id;
 83         a[id].val=m;a[id].id=id;
 84         for(i=1;i<=n;i++){
 85             u[i]=read();v[i]=read();d[i]=read();
 86             if(u[i]>m)u[i]=m;
 87             if(v[i]>m)v[i]=m;
 88             if(!mp[u[i]]){
 89                 mp[u[i]]=++id;
 90                 a[id].id=id;
 91                 a[id].val=u[i];
 92             }
 93             if(!mp[v[i]]){
 94                 mp[v[i]]=++id;
 95                 a[id].id=id;
 96                 a[id].val=v[i];
 97             }
 98             add_edge(mp[v[i]],mp[u[i]],d[i]);
 99         }
100         sort(a+1,a+id+1,cmp);
101         for(i=2;i<=id;i++){
102             add_edge(a[i].id,a[i-1].id,0);
103         }
104         LL ans;
105         if(a[1].val==1){
106             SPFA(a[1].id);ans=dis[mp[m]];
107         }
108         else ans=-1;
109         if(ans>=INF)ans=-1;
110         printf("Case #%d: %lld\n",++cas,ans);
111     }
112     return 0;
113 }