850. Dijkstra求最短路 II

代码：

#include<algorithm>
#include<iostream>
#include<cstring>
#include<queue>
#include<cmath>using namespace std;
//用pair存储编号和距离
typedef pair<int,int> PII;int n,m;
const int N = 1000010;
int e[N],w[N],ne[N],h[N],idx; 
int dist[N];
bool st[N];
//存在重边和自环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[1] = 0;//n次迭代 priority_queue<PII,vector<PII>,greater<PII>> heap;heap.push({0,1});while(heap.size()){auto t = heap.top();heap.pop();int distance = t.first;int ver = t.second;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});}}}if(dist[n] == 0x3f3f3f3f) return -1;return dist[n];
}
int main()
{cin>>n>>m;memset(h,-1,sizeof h);while(m--){int a,b,c;cin>>a>>b>>c;add(a,b,c);}int t = dijkstra();cout<<t<<endl;return 0;
}