[洛谷3371]【模板】单源最短路径
思路：Dijkstra+堆优化
1 #include<cstdio> 2 #include<cstring> 3 #include<vector> 4 #include<ext/pb_ds/priority_queue.hpp> 5 #define dis first 6 #define to second 7 #define Edge std::pair<int,int> 8 #define inf 0x7fffffff 9 #define M 500001 10 #define N 10001 11 int n,m,s; 12 int d[N]; 13 struct Graph { 14 std::vector<Edge> e[M]; 15 void add(int f,int g,int w) { 16 e[f].push_back((Edge){w,g}); 17 } 18 }; 19 Graph g; 20 inline void dijkstra() { 21 __gnu_pbds::priority_queue<Edge,std::greater<Edge> > q; 22 __gnu_pbds::priority_queue<Edge,std::greater<Edge> >::point_iterator a[n+1]; 23 for(int i=1;i<=n;i++) if(i!=s) a[i]=q.push((Edge){d[i]=inf,i}); 24 a[s]=q.push((Edge){d[s]=0,s}); 25 while(!q.empty()) { 26 Edge x=q.top(); 27 q.pop(); 28 if(x.dis==inf) continue; 29 int u=x.to; 30 for(std::vector<Edge>::iterator i=g.e[u].begin();i<g.e[u].end();i++) { 31 Edge& e=*i; 32 if(d[u]+e.dis<d[e.to]) { 33 d[e.to]=d[u]+e.dis; 34 q.modify(a[e.to],(Edge){d[e.to],e.to}); 35 } 36 } 37 } 38 } 39 int main() { 40 scanf("%d%d%d",&n,&m,&s); 41 for(int i=1;i<=m;i++) { 42 int a,b,w; 43 scanf("%d%d%d",&a,&b,&w); 44 if(a==b) continue; 45 g.add(a,b,w); 46 } 47 dijkstra(); 48 for(int i=1;i<=n;i++) { 49 printf("%d ",d[i]); 50 } 51 printf("\n"); 52 return 0; 53 }
