Dijkstra

#include<cstdio>#include<queue>#include<string>#include<sstream>#include<cstring>#include<iostream>#include<algorithm>using namespace std;const int INF = 1000000000;const int maxn = 100010; struct Edge{int from, to, dist;Edge(int u, int v, int d) : from(u), to(v), dist(d) {}};vector<Edge> edges;vector<int> G[maxn];bool done[maxn];int d[maxn];int n, m;void init(){freopen("practicein.txt","r",stdin);freopen("practiceout.txt","w",stdout);}void readdata(){cin >> n >> m;int u, v, w;for(int i = 0; i < m; i++){cin >> u >> v >> w;edges.push_back(Edge(u, v, w));G[u].push_back(i);}}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;q.push((heapnode){d[e.to],e.to});}}}}void work(){int s;dijkstra(s);}int main(){init();readdata();work();return 0;}