P4779 【模板】单源最短路径（标准版）
1 #include <bits/stdc++.h> 2 using namespace std; 3 typedef long long ll; 4 const int maxn = 1e5+5, inf = 0x3f3f3f3f; 5 struct Edge { 6 int from, to, dist; 7 }; 8 struct HeapNode { 9 int d, u; 10 bool operator < (const HeapNode& rhs) const { 11 return d > rhs.d; 12 } 13 }; 14 struct Dijkstra { 15 int n, m; 16 vector<Edge> edges; 17 vector<int> G[maxn]; 18 bool done[maxn]; 19 int d[maxn]; 20 int p[maxn]; 21 22 void init(int n) { 23 this->n = n; 24 for (int i = 1; i <= n; i++) G[i].clear(); 25 edges.clear(); 26 } 27 28 void AddEdge(int from, int to, int dist) { 29 edges.push_back((Edge){from, to, dist}); 30 m = edges.size(); 31 G[from].push_back(m-1); 32 } 33 void dijkstra(int s) { 34 priority_queue<HeapNode> Q; 35 for (int i = 1; i <= n; i++) d[i] = inf; 36 d[s] = 0; 37 memset(done, 0, sizeof(done)); 38 Q.push((HeapNode){0, s}); 39 while (!Q.empty()) { 40 HeapNode x = Q.top(); Q.pop(); 41 int u = x.u; 42 if (done[u]) continue; 43 done[u] = true; 44 for (int i = 0; i < G[u].size(); i++) { 45 Edge & e = edges[G[u][i]]; 46 if (d[e.to] > d[u] + e.dist) { 47 d[e.to] = d[u] + e.dist; 48 p[e.to] = G[u][i]; 49 Q.push((HeapNode){d[e.to], e.to}); 50 } 51 } 52 } 53 } 54 }; 55 int main() { 56 int n, m, s; scanf("%d%d%d",&n,&m,&s); 57 Dijkstra dij; 58 dij.init(n); 59 for (int i = 1; i <= m; i++) { 60 int u, v, w; scanf("%d%d%d",&u,&v,&w); 61 dij.AddEdge(u,v,w); 62 } 63 dij.dijkstra(s); 64 printf("%d",dij.d[1]==inf ? 2147483647 : dij.d[1]); 65 for (int i = 2; i <= n; i++) 66 printf(" %d",dij.d[i]==inf ? 2147483647 : dij.d[i]); 67 printf("\n"); 68 return 0; 69 }
