COGS 133. [USACO Mar08] 牛跑步 （K短路）

题目描述

传送门

题解

K短路裸题

代码

#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cstring>
#include<queue>
#define N 100003
#define inf 1000000000
#define LL long long 
using namespace std;
struct data{
    LL g,h; int x;
    bool operator<(data const &a)const {
      return g+h>a.g+a.h;
    }
};
int point[N],len[N],nxt[N],tot,n,m,can[N],ans,opt;
int point1[N],tot1,k,len1[N],nxt1[N],cnt;
LL dis[N],v[N],v1[N];
void add(int x,int y,LL z)
{
    tot++; nxt[tot]=point[x]; point[x]=tot; v[tot]=y; len[tot]=z;
    tot1++; nxt1[tot1]=point1[y]; point1[y]=tot1; v1[tot1]=x; len1[tot]=z; 
}
void spfa()
{
    memset(dis,,sizeof(dis));
    dis[]=; can[]=;
    queue<int> p; p.push();
    while (!p.empty()) {
        int now=p.front(); p.pop();
        for (int i=point1[now];i;i=nxt1[i])
         if (dis[v1[i]]>dis[now]+len1[i]) {
            dis[v1[i]]=dis[now]+len1[i];
            if (!can[v1[i]]) {
                can[v1[i]]=;
                p.push(v1[i]);
             }
         }
        can[now]=;
    }
    //cout<<dis[0]<<" "<<dis[n]<<endl;
}
void Astar()
{
    priority_queue<data> p;
    data a,nt; a.x=n; a.g=; a.h=dis[n];
    p.push(a);
    while (!p.empty()) {
        data now=p.top(); p.pop();
        if (now.x==) {
            cnt++; printf("%lld\n",now.g);
            if (cnt==k) return;
        }
        for (int i=point[now.x];i;i=nxt[i]){
            nt.x=v[i]; nt.g=now.g+len[i];
            nt.h=dis[v[i]]; p.push(nt);
        }
    }
}
int main()
{
    freopen("cowjog.in","r",stdin);
    freopen("cowjog.out","w",stdout);
    scanf("%d%d%d",&n,&m,&k);
    for (int i=;i<=m;i++) {
        int x,y,z; scanf("%d%d%d",&x,&y,&z);
        if (x<y) swap(x,y);
        add(x,y,z);
    }
    spfa();
    Astar();
    for (int i=cnt+;i<=k;i++) printf("-1\n");
}