POJ3159 Candies

 #include <iostream>
 #include <queue>
 #include <cstring>
 #define maxn 30005
 #define scanf(x) scanf("%d", &x)
 using namespace std;

 struct CNode
 {
     int next;    // index of the next vector from the same vertex
     int k;       // the end vertex of the vector
     int w;
     int d;       // distence from k to the source point
 }edges[*maxn];

 bool operator < (const CNode &C1, const CNode &C2)
 {
     return C1.w > C2.w;
 }

 priority_queue<CNode> pq;
 int cnt, N, head[maxn];
 bool bUsed[maxn];

 void build(int u, int v, int w)
 {
     edges[cnt].k = v;
     edges[cnt].w = w;
     edges[cnt].d = w;
     edges[cnt].next = head[u];
     head[u] = cnt++;
 }

 int main()
 {
     int M;
     CNode p;
     cnt = ;
     memset(head, -, sizeof(head));
     memset(bUsed, , sizeof(bUsed));
     scanf(N), scanf(M);
     while (M--){
         int a, b, r;
         scanf(a), scanf(b), scanf(r);
         build(a, b, r);
     }
     edges[].k = ;
     edges[].w = ;
     edges[].d = ;
     edges[].next = -;
     pq.push(edges[]);
     while (!pq.empty()) {
         p = pq.top(); pq.pop();
         if (bUsed[p.k])continue;
         else bUsed[p.k] = ;
         if (p.k == N)break;
         for (int i = head[p.k]; i != -; i = edges[i].next) {
             if (bUsed[edges[i].k])continue;
             edges[i].d = p.d + edges[i].w;
             pq.push(edges[i]);
         }
     }
     printf("%d\n", p.d);
     return ;
 }