hihocoder #1109 最小生成树三·堆优化的Prim算法

#include
#include
#include
#include
using namespace std;   
#define FOR(i,b,e) for(int i=(b);i<=(e);i++)  
#define FORE(i,b,e) for(int i=(b);i>=(e);i--) 
#define lson(x) (x<<1)
#define rson(x) ((x<<1)+1)
#define maxnum  100003
#define maxedge 1000003
#define INF     100003
struct edge{
int nxt;
int v;
int val;
}e[maxedge*2];
int edgenum=0;
int head[maxnum];
int heap[2*maxedge],heapnum=0;
bool visit[maxnum];





int pop_heap(){
    int res=heap[1];
    int h=heap[heapnum];
    heapnum--;

    int hole = 1;
    while(hole <= heapnum){
        int index=hole<<1;
        if(index>heapnum) break;
        index = (index+1>heapnum||e[heap[index]].val<=e[heap[index+1]].val)?index:index+1;
        if(e[heap[index]].valelse break;
        hole=index;

    }
    heap[hole]=h;
    return res;
}

void insert(int ed){
    int i=++heapnum; 
    while(i>1&&e[heap[i/2]].val>e[ed].val){
        heap[i]=heap[i/2];
        i/=2;
    }
    heap[i]=ed;
}

int main()
{
#ifdef DEBUG_
    ifstream fin("G:/1.txt");
#define cin fin
#endif
    int N,M,u,v,val;
    memset(e,0,sizeof(e));
    memset(head,-1,sizeof(head));
    memset(visit,0,sizeof(visit));
    cin>>N>>M;
    FOR(i,0,M-1){
        cin>>u>>v>>val;
        e[edgenum].v=v;
        e[edgenum].val=val;
        e[edgenum].nxt=head[u];
        head[u]=edgenum++;
        e[edgenum].v=u;
        e[edgenum].val=val;
        e[edgenum].nxt=head[v];
        head[v]=edgenum++;
    }


    int res = 0;
    int left = N - 1;
    visit[1] = true;
    for (int i = head[1]; i != -1; i = e[i].nxt)
        insert(i);

    while (heapnum!=0 && left) {
        int ed = pop_heap();
        if (visit[e[ed].v])
          continue;
        res += e[ed].val;
        left--;
        visit[e[ed].v] = true;
        for (int i = head[e[ed].v]; i != -1; i = e[i].nxt) {
            if (!visit[e[i].v])
                insert(i);
        }
  }


    cout<return 0;
}