【洛谷1339 [USACO09OCT]】热浪Heat Wave 图论+最短路

AC代码

#include<bits/stdc++.h>
using namespace std;
const int MAXN=62000+10,INF=999999;
struct Edge{
	int u,v,w,next;
}edge[MAXN];
int head[MAXN],n,m,s,t,dist[MAXN],cnt;
bool vis[MAXN];
void addedge(int x,int y,int z){
	edge[cnt].u=x;
	edge[cnt].v=y;
	edge[cnt].w=z;
	edge[cnt].next=head[x];
	head[x]=cnt++;
}
void spfa(){
	queue<int>q;
	for(int i=1;i<=n;i++){
		dist[i]=INF;
		vis[i]=false;
	}
	dist[s]=0;
	vis[s]=true;
	q.push(s);
	while(!q.empty()){
		int k=q.front();
		q.pop();
		vis[k]=false;
		for(int i=head[k];i!=-1;i=edge[i].next){
			int to=edge[i].v;
			if(dist[to]==INF||dist[to]>dist[k]+edge[i].w){
				dist[to]=dist[k]+edge[i].w;
				if(vis[to]==false){
					vis[to]=true;
					q.push(to);
				}
			}
		}
	}
}
int main()
{
	memset(head,-1,sizeof(head));
	scanf("%d%d%d%d",&n,&m,&s,&t);
	for(int i=1;i<=m;i++){
		int a,b,c;
		scanf("%d%d%d",&a,&b,&c);
		addedge(a,b,c);addedge(b,a,c);
	}
	spfa();
	printf("%d",dist[t]);
	return 0;
}