Dijkstra（最短路求解）

模板：

#include<iostream>

#include<cstdio>

#include<cstring>

#include<queue>

#include<algorithm>

using namespace std;

typedef __int64 LL;

const int maxn = 2005;

const int INF = 0x3f3f3f3f;

struct Edge{

    int u,v,next;

    LL w;

    bool operator < (const Edge & a)const

    {

        return w > a.w;

    }

}edge[maxn<<1] ;

int tot = 0,head[maxn];

bool vis[maxn];

LL dis[maxn];

void addedge(int u,int v,LL w)

{

    edge[tot] = (Edge){u,v,head[u],w

    };

    head[u] = tot++;

}

void Dijkstra()

{

    priority_queue<Edge>que;

    Edge p;

    memset(dis,INF,sizeof(dis));

    memset(vis,false,sizeof(vis));

    p.v = 1;

    que.push(p);

    dis[1] = 0;

    while (!que.empty())

    {

        p = que.top();

        que.pop();

        int u = p.v;

        if (vis[u]) continue;

        vis[u] = true;

        for (int i = head[u];i != -1;i = edge[i].next)

        {

            int v = edge[i].v;

            if (dis[u] + edge[i].w < dis[v])

            {

                dis[v] = dis[u] + edge[i].w;

                p.u = u,p.v = v,p.w = dis[v];

                que.push(p);

            }

        }

    }

}

int main()

{

    //freopen("input.txt","r",stdin);

    int T,N,u,v;

    LL w;

    memset(head,-1,sizeof(head));

    scanf("%d%d",&T,&N);

    for (int i = 0;i < T;i++)

    {

        scanf("%d%d%I64d",&u,&v,&w);

        addedge(u,v,w);

        addedge(v,u,w);

    }

    Dijkstra();

    printf("%I64d\n",dis[N]);

    return 0;

}