白皮书328dijkstra模板

#include<bits/stdc++.h>
using namespace std;
const int maxn=2005;
const int INF=0x3fffffff;
struct Edge
{
    int from,to,dist;
};
struct HeapNode
{
    int d,u;
    bool operator <(const HeapNode& rhs)const
    {
        return d>rhs.d;
    }
};

struct Dijkstra
{
    int n,m;
    vector<Edge>edges;
    vector<int>G[maxn];
    bool done[maxn];
    int d[maxn];//s到各点的距离
    int p[maxn];//最短路径中的上一条边
    void init(int n)
    {
        this->n=n;
        for (int i=0; i<=n; i++ )
            G[i].clear();
        edges.clear();
    }
    void AddEdge(int from,int to,int dist)
    {
        edges.push_back((Edge)
        {
            from,to,dist
        });
        m=edges.size();
        G[from].push_back(m-1);
    }

    void dijkstra(int s)
    {
        priority_queue<HeapNode> Q;
        for (int i=0; i<=n ; i++ )
            d[i]=INF;
        d[s]=0;
        memset(done,0,sizeof(done));
        Q.push((HeapNode)
        {
            0,s
        });
        while(!Q.empty())
        {
            HeapNode x= Q.top();
            Q.pop();
            int u=x.u;
            if(done[u])continue;
            done[u]=true;
            for (int i=0; i<G[u].size() ; i++ )
            {
                Edge& e=edges[G[u][i]];
                if(d[e.to]>d[u]+e.dist)
                {
                    d[e.to]=d[u]+e.dist;
                    p[e.to]=G[u][i];
                    Q.push((HeapNode)
                    {
                        d[e.to],e.to
                    });
                }
            }
        }
    }
};

int main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    Dijkstra ans;
    int n,m;
    while(cin>>n>>m)
    {
        ans.init(n);
        for (int i=0; i<m ; i++ )
        {
            int u,v,cost;
            cin>>u>>v>>cost;
            ans.AddEdge(u,v,cost);
            ans.AddEdge(v,u,cost);
        }
        int s,t;
        cin>>s>>t;
        ans.dijkstra(s);
        if(ans.d[t]==INF)cout<<-1<<endl;
        else cout<<ans.d[t]<<endl;
    }
    return 0;
}