裸dijkstra+heap

C++ 代码

#include<bits/stdc++.h>
using namespace std;
const int N=6210*2;
int n,m,s,t,dist[N],h[N],e[N],w[N],ne[N],idx;
bool st[N];
typedef pair<int,int> PII;
void add(int a,int b,int c)
{
    e[idx]=b,w[idx]=c,ne[idx]=h[a],h[a]=idx++;
}
int dijkstra()
{
    memset(dist,0x3f,sizeof dist);
    dist[s]=0;
    priority_queue<PII,vector<PII>,greater<PII> > heap;
    heap.push({0,s});
    while(!heap.empty())
    {
        PII t=heap.top();
        heap.pop();
        int ver=t.second,distance=t.first;
        if(st[ver]) continue;
        st[ver]=true;
        for(int i=h[ver];i!=-1;i=ne[i])
        {
            int j=e[i];
            if(dist[j]>distance+w[i])
            {
                dist[j]=distance+w[i];
                heap.push({dist[j],j});
            }
        }
    }
    return dist[t];
}
int main()
{
    cin>>n>>m>>s>>t;
    memset(h,-1,sizeof h);
    while(m--)
    {
        int a,b,c;
        cin>>a>>b>>c;
        add(a,b,c);add(b,a,c);
    }
    cout<<dijkstra();
    return 0;
}