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 }
