Dijkstra模板

Posted 2020-10-24 third2333

 1 #include <bits/stdc++.h> 
 2 #define For(i,j,k) for(int i=j;i<=k;i++)
 3 #define Dow(i,j,k) for(int i=j;i>=k;i--)
 4 #define LL long long
 5 using namespace std ;
 6 inline int read() {
 7     int x = 0, f = 1;
 8     char ch = getchar();
 9     while(ch<‘0‘||ch>‘9‘) { if(ch==‘-‘) f = -1; ch = getchar(); }
10     while(ch>=‘0‘&&ch<=‘9‘) { x = x * 10+ch-48; ch = getchar(); }
11     return x * f;
12 }
13 inline void write(LL x) {
14     if( x < 0 ) putchar(‘-‘);
15     if( x > 9 ) write(x/10);
16     putchar(x%10+48);
17 }
18 const int N = 10011, M = 500011; 
19 const LL INF = 1e16; 
20 int n, m, S, nedge; 
21 int head[N], vis[N];
22 LL dist[N];   
23 struct edge{
24     int to, pre, val; 
25 }e[M];
26 struct node{
27     int id; 
28     LL val; 
29     friend bool operator <(node a, node b) {
30         return a.val > b.val; 
31     }
32 };
33 priority_queue<node> Q; 
34 inline void add(int x, int y, int v) {
35     e[++nedge] = (edge){y, head[x], v};
36     head[x] = nedge; 
37 }
38 void Dijkstra(int S) {
39     For(i, 0, n) dist[i] = INF; 
40     For(i, 0, n) vis[i] = 0; 
41     dist[S] = 0; 
42     while(!Q.empty()) Q.pop(); 
43     
44     Q.push((node){S, 0}); 
45     while(!Q.empty()) {
46         node p = Q.top(); Q.pop(); 
47         int u = p.id; 
48         if(vis[u]) continue; 
49         vis[u] = 1; 
50         for(int i=head[u]; i; i=e[i].pre) {       
51             int v = e[i].to; 
52             if(dist[u]+e[i].val < dist[v]) {
53                 dist[v] = dist[u]+e[i].val; 
54                 Q.push((node){v, dist[v]}); 
55             }
56         }
57     }
58 } 
59 
60 int main() {
61     n = read(); m = read(); S = read(); 
62     For(i, 1, m) {
63         int x=read(), y=read(), v=read();
64         add(x, y, v); 
65     } 
66     Dijkstra(S);
67     For(i, 1, n) 
68         if(dist[i] != INF) write(dist[i]), putchar(‘ ‘); 
69         else printf("2147483647 "); 
70     return 0; 
71 }