poj 3159 Candies

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define Max_N 200000
#define INF 0x3f3f3f3f
typedef struct info{int dist,vertex;}pair;
typedef struct pri_heap
{
    pair tp[Max_N];
    int nSize;
}Heap;
Heap que;
int N,M,vis[Max_N],dist[Max_N],first[Max_N],u[Max_N],v[Max_N],w[Max_N],next[Max_N];
void Init()
{
    que.nSize=0;
}
int empty()
{
    return 0==que.nSize;
}
void push(int dist,int v)
{
    int i=que.nSize++;
    pair tmp;
    tmp.dist=dist,tmp.vertex=v;
    while(i>0)
    {
        int p=(i-1)>>1;
        if(que.tp[p].dist<=tmp.dist) break;
        que.tp[i]=que.tp[p];
        i=p;
    }
    que.tp[i]=tmp;
}
pair pop()
{
    pair ret=que.tp[0];
    pair tmp=que.tp[--que.nSize];
    int i=0;
    while(i*2+1 < que.nSize)
    {
        int a=i*2+1,b=i*2+2;
        if(i*2+2 < que.nSize && que.tp[a].dist > que.tp[b].dist) a=b;
        if(que.tp[a].dist >= tmp.dist) break;
        que.tp[i]=que.tp[a];
        i=a;
    }
    que.tp[i]=tmp;
    return ret;
}
void dijkstra()
{
    int i;
    Init();
    memset(vis,0,sizeof(vis));
    for(i=0;i<N;i++) dist[i]=(i==0?0:INF);
    push(0,0);
    while(!empty())
    {
        pair pii=pop();
        int x=pii.vertex;
        if(vis[x]) continue;
        vis[x]=1;
        for(i=first[x];-1!=i;i=next[i])
        {
            if(dist[v[i]] > dist[x] + w[i])
            {
                dist[v[i]] = dist[x] + w[i];
                push(dist[v[i]],v[i]);
            }
        }
    }
    printf("%d\n",dist[N-1]);
}
int main()
{
    #ifdef LOCAL
    freopen("input.txt","r",stdin);
    #endif
    int e;
    while(EOF!=scanf("%d %d",&N,&M))
    {
        memset(first,-1,sizeof(first));
        for(e=0;e<M;e++)
        {
            scanf("%d %d %d",&u[e],&v[e],&w[e]);
            --u[e],--v[e];
            next[e]=first[u[e]];
            first[u[e]]=e;
        }
        dijkstra();
    }
    return 0;
}