Dijkstra最短路

//普通版本 O（n^2）
int vis[n],d[n];
memset(vis,0,sizeof(vis));
for(int i=0;i<n;i++) d[i]=(i==0? 0:inf);
for(int i=0;i<n;i++){
    int x,m=inf;
    for(int y=0;y<n;y++){
        if(!vis[y]&&d[y]<m) m=d[x=y];
    }
    vis[x]=1;
    for(int y=0;y<n;y++) d[y]=min(d[y],d[x]+w[x][y]);
}

//队列优化 O（Elog(N)）
const int inf=999999999;

struct Edge{
    int from,to,dist;
    Edge(int u,int v,int d):from(u),to(v),dist(d){}
};

struct Dijkstra{
     int n,m;
    vector<Edge> edges;
    vector<int > G[maxn];
    bool done[maxn];
    int d[maxn];
    int p[maxn];
    
    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);
    }

    struct HeapNode{
        int d,u;
        bool operator < (const HeapNode& rhs) const{
            return d>rhs.d;
        }
    };

    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});
                }
            }
        }
    }
};