hihocoder1081：最短路（Dijkstra）

hihocoder 1081

题解：Dijkstra裸题，有重复的边和环没关系。

代码：

#include <bits/stdc++.h>
using namespace std;
typedef pair<int,int>pii;
int const inf = 0x7f7f7f7f;
int const N = 1000 + 10;
int n,m,s,t,d[N];
struct Edge
{
	int from,to,dist;
	Edge(){}
	Edge(int f,int t,int d):from(f),to(t),dist(d){}
};
vector<Edge>G[N];
priority_queue<pii,vector<pii>,greater<pii> >q;
int Dijkstra(int s){
	for(int i=1;i<=n;i++)	d[i] = inf;
	q.push(make_pair(0,s));
	d[s] = 0;
	while(!q.empty()){
		pii p = q.top();	q.pop();
		int u = p.second;
		if(d[u]<p.first)	continue;
		for(int i=0;i<G[u].size();i++){
			Edge e = G[u][i];
			if(d[e.to]>d[e.from]+e.dist){
				d[e.to] = d[e.from]+e.dist;
				q.push(make_pair(d[e.to],e.to));
			}
		}
	}
	return d[t];
}
int main(){
	scanf("%d%d%d%d",&n,&m,&s,&t);
	for(int i=1;i<=m;i++){
		int from,to,dist;
		scanf("%d%d%d",&from,&to,&dist);
		G[from].push_back(Edge(from,to,dist));
		G[to].push_back(Edge(to,from,dist));
	}
	printf("%d\n",Dijkstra(s));
	return 0;
}