POJ3159 Candies

 1 #include <iostream>
 2 #include <queue>
 3 #include <cstring>
 4 #define maxn 30005
 5 #define scanf(x) scanf("%d", &x)
 6 using namespace std;
 7 
 8 struct CNode
 9 {
10     int next;    // index of the next vector from the same vertex
11     int k;       // the end vertex of the vector
12     int w;
13     int d;       // distence from k to the source point
14 }edges[5*maxn];
15 
16 bool operator < (const CNode &C1, const CNode &C2)
17 {
18     return C1.w > C2.w;
19 }
20 
21 priority_queue<CNode> pq;
22 int cnt, N, head[maxn];
23 bool bUsed[maxn];
24 
25 void build(int u, int v, int w)
26 {
27     edges[cnt].k = v;
28     edges[cnt].w = w;
29     edges[cnt].d = w;
30     edges[cnt].next = head[u];
31     head[u] = cnt++;
32 }
33 
34 int main()
35 {
36     int M;
37     CNode p;
38     cnt = 1;
39     memset(head, -1, sizeof(head));
40     memset(bUsed, 0, sizeof(bUsed));
41     scanf(N), scanf(M);
42     while (M--){
43         int a, b, r;
44         scanf(a), scanf(b), scanf(r);
45         build(a, b, r);
46     }
47     edges[0].k = 1;
48     edges[0].w = 0;
49     edges[0].d = 0;
50     edges[0].next = -1;
51     pq.push(edges[0]);
52     while (!pq.empty()) {
53         p = pq.top(); pq.pop();
54         if (bUsed[p.k])continue;
55         else bUsed[p.k] = 1;
56         if (p.k == N)break;
57         for (int i = head[p.k]; i != -1; i = edges[i].next) {
58             if (bUsed[edges[i].k])continue;
59             edges[i].d = p.d + edges[i].w;
60             pq.push(edges[i]);
61         }
62     }
63     printf("%d\n", p.d);
64     return 0;
65 }