[BZOJ2124] 等差子序列 

/*线段树维护区间HASH值*/
 1 #include <cmath>
 2 #include <cstdio>
 3 #include <cstdlib>
 4 #include <cstring>
 5 #include <iostream>
 6 #include <algorithm>
 7 # define maxn 10010
 8 # define p 31
 9 using namespace std;
10 typedef unsigned long long ULL;
11 void fen(){cout<<"-------------------"<<endl;}
12 ULL px[maxn];
13 int T,n;
14 void beg(){px[0]=1; for(int i=1;i<=10000;i++) px[i]=px[i-1]*p;}
15 int num[maxn];
16 struct XDS{
17     struct TR{
18         int ls,rs,t;
19         ULL hs;
20     }tr[4*maxn];
21     void pushup(int rt,int len1,int len2,int od){
22         if(!od){
23             tr[rt].hs=tr[rt<<1].hs*px[len2]+tr[rt<<1|1].hs;
24         }
25         else{
26             tr[rt].hs=tr[rt<<1|1].hs*px[len1]+tr[rt<<1].hs;
27         }
28     }
29     void Add(int rt,int l,int r,int now,int od){
30         if(l==r){tr[rt].t=1; tr[rt].hs=1; return;}
31         int mid=(l+r)>>1;
32         if(now<=mid) Add(rt<<1,l,mid,now,od);
33         else Add(rt<<1|1,mid+1,r,now,od);
34         pushup(rt,mid-l+1,r-mid,od);
35     }
36     ULL Query(int left,int right,int rt,int l,int r,int od){
37         ULL ret=0;
38         if(left<=l && r<=right){
39             if(!od){ret+=tr[rt].hs*px[right-r];}
40             else{ret+=tr[rt].hs*px[l-left];}
41             return ret;
42         }
43         int mid=(l+r)>>1;
44         if(left<=mid) ret+=Query(left,right,rt<<1,l,mid,od);
45         if(right>mid) ret+=Query(left,right,rt<<1|1,mid+1,r,od);
46         return ret;
47     }
48 }z,f;
49 void work(){
50     memset(f.tr,0,sizeof(f.tr));
51     memset(z.tr,0,sizeof(z.tr));
52     int ak;
53     for(int i=1;i<=n;i++){
54         ak=min(num[i]-1,n-num[i]);
55         z.Add(1,1,n,num[i],0); f.Add(1,1,n,num[i],1);
56         if(ak==0) continue;
57         ULL now1=z.Query(num[i]-ak,num[i]-1,1,1,n,0);
58         ULL now2=f.Query(num[i]+1,num[i]+ak,1,1,n,1);
59         if(now1!=now2){
60             printf("Y\n"); return;
61         }
62     }
63     printf("N\n"); return;
64 }
65 int main(){
66     // freopen("a.in","r",stdin);
67     scanf("%d",&T);
68     beg();
69     while(T--){
70         scanf("%d",&n);
71         for(int i=1;i<=n;i++) scanf("%d",&num[i]);
72         work();    
73     }
74     return 0;
75 }

 

posted @ 2017-09-27 12:07  Nawox  阅读(168)  评论(0)    收藏  举报