Dijkstra的heap优化

为了将最小费用最大流的spfa优化，决定将spfa换成heap优化的Dijkstra。

所以还得现学。。。

stl大法好。

——附带码

 1 #include <cstdio>
 2 #include <queue>
 3 #include <cstring>
 4 #define Heap pair<int, int>
 5
 6 using namespace std;
 7
 8 const int INF = 2147483647;
 9 int n, m, t, cnt;
10 int next[1000001], to[1000001], val[1000001], head[10001], dis[10001];
11 priority_queue <Heap, vector <Heap>, greater <Heap> > q;
12
13
14 inline void add(int a, int b, int c)
15 {
16     to[cnt] = b;
17     val[cnt] = c;
18     next[cnt] = head[a];
19     head[a] = cnt++;
20 }
21
22 inline void Dijkstra(int s)
23 {
24     int i, v;
25     Heap u;
26     for(i = 1; i <= n; i++) dis[i] = INF;
27     dis[s] = 0;
28     q.push(make_pair(0, s));
29     while(!q.empty())
30     {
31         u = q.top();
32         q.pop();
33         if(u.first != dis[u.second]) continue;
34         for(i = head[u.second]; i != -1; i = next[i])
35         {
36             v = to[i];
37             if(dis[v] > dis[u.second] + val[i])
38             {
39                 dis[v] = dis[u.second] + val[i];
40                 q.push(make_pair(dis[v], v));
41             }
42         }
43     }
44 }
45
46 int main()
47 {
48     int i, j, a, b, c, s;
49     scanf("%d %d %d", &n, &m, &s);
50     memset(head, -1, sizeof(head));
51     for(i = 1; i <= m; i++)
52     {
53         scanf("%d %d %d", &a, &b, &c);
54         add(a, b, c);
55     }
56     Dijkstra(s);
57     for(i = 1; i <= n; i++) printf("%d ", dis[i]);
58     return 0;
59 }