重铸华农荣光 我辈义不容辞

The seventeenth day - Heap-Dijkstra

#include<iostream>
#include<cstring>
#include<algorithm>
#include<queue>
using namespace std;

const int N=150010;
typedef pair<int,int> PII;
int n,m;
int h[N],e[N],ne[N],w[N],idx;
int dist[N];
bool st[N];

void add(int a,int b,int c)
{
    e[idx]=b,ne[idx]=h[a],w[idx]=c,h[a]=idx++;
}

int Dijkstra()
{
    memset(dist,0x3f,sizeof dist);
    dist[1]=0;
    priority_queue<PII,vector<PII>,greater<PII>> heap;//小根堆
    heap.push({0,1});
    while(heap.size()){
        auto 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]>dist[ver]+w[i])
            {
                dist[j]=dist[ver]+w[i];
                heap.push({dist[j],j});
            }
        }
    }
    if(dist[n]==0x3f3f3f3f) return -1;
    return dist[n];
}

int main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    cin>>n>>m;
    memset(h,-1,sizeof h);
    while(m--){
        int a,b,c;
        cin>>a>>b>>c;
        add(a,b,c);
    }

    cout<<Dijkstra();
    return 0;
}