BZOJ3408: [Usaco2009 Oct]Heat Wave 热浪

最短路模板。选迪杰。

#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include<algorithm>
#include<queue>
//#include<iostream>
using namespace std;

int n,m,s,t;
#define maxn 2511
#define maxm 12411
const int inf=0x3f3f3f3f;
struct Graph
{
    struct Edge{int to,v,next;}edge[maxm];int first[maxn],le;
    Graph() {memset(first,0,sizeof(first));le=2;}
    void in(int x,int y,int v) {Edge &e=edge[le];e.to=y;e.v=v;e.next=first[x];first[x]=le++;}
    void insert(int x,int y,int v) {in(x,y,v);in(y,x,v);}
    int dis[maxn];bool vis[maxn];
    struct qnode
    {
        int id,v;
        bool operator < (const qnode &b) const {return v<b.v;}
        bool operator > (const qnode &b) const {return v>b.v;}
    };
    priority_queue<qnode,vector<qnode>,greater<qnode> > q;
    void dijkstra(int s)
    {
        for (int i=1;i<=n;i++) dis[i]=inf;
        memset(vis,0,sizeof(vis));
        q.push((qnode){s,0});
        while (!q.empty())
        {
            const int x=q.top().id,d=q.top().v;q.pop();
            if (vis[x]) continue;
            vis[x]=1;dis[x]=d;
            for (int i=first[x];i;i=edge[i].next)
            {
                const Edge &e=edge[i];
                if (dis[e.to]>d+e.v)
                {
                    dis[e.to]=d+e.v;
                    q.push((qnode){e.to,dis[e.to]});
                }
            }
        }
    }
}g;
int x,y,v;
int main()
{
    scanf("%d%d%d%d",&n,&m,&s,&t);
    for (int i=1;i<=m;i++)
    {
        scanf("%d%d%d",&x,&y,&v);
        g.insert(x,y,v);
    }
    g.dijkstra(s);
    printf("%d
",g.dis[t]);
    return 0;
}