HDU 6136 Death Podracing（循环链表）

#include <cstdio>
#include <algorithm>
#include <cstring>
#include <queue>
using namespace std;
const int N=100010,INF=0x3f3f3f3f;
struct data{int d,v,pw;}p[N];
bool cmp(data a,data b){return a.d<b.d;}
int T,Del[N],n,L,nxt[N],pre[N];
struct Frac{
    int Den,Num;
    Frac(){}
    Frac(int _Num,int _Den){Den=_Den;Num=_Num;}
    bool operator <(const Frac &rhs)const{return 1LL*Num*rhs.Den<1LL*rhs.Num*Den;}
};
Frac Cal(data a,data b){
    int V=b.v-a.v,D=a.d-b.d;
    if(D<0)D+=L; if(V<0)V=-V,D=L-D;
    if(V==0)return Frac(INF,1);
    int GCD=__gcd(V,D);
    return Frac(D/GCD,V/GCD);
}
struct Relt{
    int a,b;Frac t;
    Relt(){}
    Relt(int _a,int _b,Frac _t){a=_a;b=_b;t=_t;}
    bool operator < (const Relt &x)const{return x.t<t;}
};
priority_queue<Relt> Q;
void Out(int x){
    Del[x]=1;
    nxt[pre[x]]=nxt[x];
    pre[nxt[x]]=pre[x];
    Q.push(Relt(pre[x],nxt[x],Cal(p[pre[x]],p[nxt[x]])));
}
int main(){
    scanf("%d",&T);
    while(T--){
        scanf("%d%d",&n,&L);
        memset(Del,0,sizeof(Del));
        for(int i=0;i<n;i++)scanf("%d",&p[i].d),p[i].pw=i;
        for(int i=0;i<n;i++)scanf("%d",&p[i].v);
        sort(p,p+n,cmp); while(!Q.empty())Q.pop();
        for(int i=0;i<n;i++){
            nxt[i]=(i+1)%n; pre[i]=(i-1+n)%n;
            Q.push(Relt(i,nxt[i],Cal(p[i],p[nxt[i]])));
        }int Lft=n; Frac Ans;
        while(Q.size()){
            Relt x=Q.top(); Q.pop();
            if(Del[x.a]||Del[x.b])continue; 
            if(--Lft==1){Ans=x.t;break;}
            if(p[x.a].pw>p[x.b].pw)Out(x.b);
            else Out(x.a);
       }printf("%d/%d\n",Ans.Num,Ans.Den);
    }return 0;
}