CodeForcesGym 100753E Change of Scenery

Change of Scenery

Time Limit: 10000ms

Memory Limit: 262144KB

This problem will be judged on CodeForcesGym. Original ID: 100753E
64-bit integer IO format: %I64d      Java class name: (Any)

 

解题：最短路

#include <bits/stdc++.h>
using namespace std;
typedef pair<int,int> pii;
const int maxn = 10010;
struct arc{
    int to,cost,next;
    arc(int x = 0,int y = 0,int z = -1){
        to = x;
        cost = y;
        next = z;
    }
}e[2010000];
int head[maxn],cnt[maxn],d[maxn],tot,N,M,K;
void add(int u,int v,int w){
    e[tot] = arc(v,w,head[u]);
    head[u] = tot++;
}
priority_queue<pii,vector<pii>,greater<pii>>q;
bool done[maxn];
void dijkstra(){
    while(!q.empty()) q.pop();
    memset(d,0x3f,sizeof d);
    memset(cnt,0,sizeof cnt);
    q.push(pii(d[1] = 0,cnt[1] = 1));
    while(!q.empty()){
        int u = q.top().second;
        q.pop();
        if(done[u]) continue;
        done[u] = true;
        for(int i = head[u]; ~i; i = e[i].next){
            if(d[e[i].to] > d[u] + e[i].cost){
                d[e[i].to] = d[u] + e[i].cost;
                cnt[e[i].to] = cnt[u];
                q.push(pii(d[e[i].to],e[i].to));
            }else if(d[e[i].to] == d[u] + e[i].cost)
                cnt[e[i].to]++;
        }
    }
}
int main(){
    int x,u,v,w;
    while(~scanf("%d%d%d",&N,&M,&K)){
        memset(head,-1,sizeof head);
        while(K--) scanf("%d",&x);
        for(int i = tot = 0; i < M; ++i){
            scanf("%d%d%d",&u,&v,&w);
            add(u,v,w);
            add(v,u,w);
        }
        dijkstra();
        puts(cnt[N] > 1?"yes":"no");
    }
    return 0;
}
/*
3 3 3
1 2 3
1 2 1
2 3 2
1 3 3
4 5 2
1 4
1 2 2
2 4 1
1 3 1
3 4 2
1 4 2
*/