spfa模版

#include<bits/stdc++.h>

using namespace std;

int n,m;//点边
int beginn;

int u[],v[],w[];
int first[],nextt[]; 

long long dis[];
int book[];

int k2=;

void clean()
{
    for(int i=;i<=n;i++)
    {
        dis[i]=;
        if(i==beginn) dis[i]=;

        first[i]=-;
    }

    for(int i=;i<=m;i++)
    {
        nextt[i]=-;
    }
}

void make_edge(int _a,int _b,int _c)
{
    k2++;
    u[k2]=_a;
    v[k2]=_b;
    w[k2]=_c;
    nextt[k2]=first[u[k2]];
    first[u[k2]]=k2;
}

deque<int> q; 

int main()
{
    cin>>n>>m>>beginn;

    clean();

    for(int i=;i<=m;i++)
    {
        int a,b,c;
        cin>>a>>b>>c;
        make_edge(a,b,c);
    }

    book[beginn]=;
    q.push_front(beginn);

    while(!q.empty())
    {
        int now_node=q.front();
        book[now_node]=;
        q.pop_front();

        int k=first[u[now_node]];
        while(k!=-)
        {
            if(dis[v[k]]>dis[u[k]]+w[k])
            {
                dis[v[k]]=dis[u[k]]+w[k];
                if(book[v[k]]==)
                {
                    book[v[k]]=;
                    if(!q.empty()&&dis[v[k]]<dis[q.front()])
                    {
                        q.push_front(v[k]);
                    }
                    else q.push_back(v[k]);
                }
            }
            k=nextt[k];
        }
    }

    for(int i=;i<=n;i++)
    {
        if(i==beginn) cout<<"0 ";
        else cout<<dis[i]<<" ";
    }

    cout<<endl;
    return ;
}

spfa未调过