Dijkstra(最短路求解)

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;
}