【HDOJ6621】K-th Closest Distance（主席树，二分）

题意：给定一个长为n的序列，有m次强制在线的询问，每次询问位置【L,R】中abs(a[i]-p)第k小的值

n,m<=1e5，a[i]<=1e6，p<=1e6，k<=169

思路：主席树外面套个二分

  1 #include<bits/stdc++.h>
  2 using namespace std;
  3 typedef long long ll;
  4 typedef unsigned int uint;
  5 typedef unsigned long long ull;
  6 typedef pair<int,int> PII;
  7 typedef pair<ll,ll> Pll;
  8 typedef vector<int> VI;
  9 #define N  1100000
 10 #define M  4100000
 11 #define fi first
 12 #define se second
 13 #define MP make_pair
 14 #define pi acos(-1)
 15 #define mem(a,b) memset(a,b,sizeof(a))
 16 #define rep(i,a,b) for(int i=(int)a;i<=(int)b;i++)
 17 #define per(i,a,b) for(int i=(int)a;i>=(int)b;i--)
 18 #define lowbit(x) x&(-x)
 19 #define Rand (rand()*(1<<16)+rand())
 20 #define id(x) ((x)<=B?(x):m-n/(x)+1)
 21 #define ls p<<1
 22 #define rs p<<1|1
 23 
 24 const ll MOD=998244353,inv2=(MOD+1)/2;
 25       double eps=1e-6;
 26       int INF=1e9;
 27 
 28 struct node
 29 {
 30     int l,r,s;
 31 }t[N*20];
 32 
 33 int root[N],cnt;
 34 
 35 int read()
 36 {
 37    int v=0,f=1;
 38    char c=getchar();
 39    while(c<48||57<c) {if(c=='-') f=-1; c=getchar();}
 40    while(48<=c&&c<=57) v=(v<<3)+v+v+c-48,c=getchar();
 41    return v*f;
 42 }
 43 
 44 void update(int l,int r,int x,int &p)
 45 {
 46     t[++cnt]=t[p];
 47     p=cnt;
 48     t[p].s++;
 49     if(l==r) return;
 50     int mid=(l+r)>>1;
 51     if(x<=mid) update(l,mid,x,t[p].l);
 52      else update(mid+1,r,x,t[p].r);
 53 }
 54 
 55 int query(int l,int r,int x,int y,int p1,int p2)
 56 {
 57     if(x<=l&&r<=y) return t[p2].s-t[p1].s;
 58     int mid=(l+r)>>1;
 59     int tmp=0;
 60     if(x<=mid) tmp+=query(l,mid,x,y,t[p1].l,t[p2].l);
 61     if(y>mid) tmp+=query(mid+1,r,x,y,t[p1].r,t[p2].r);
 62     return tmp;
 63 }
 64 
 65 int main()
 66 {
 67     //freopen("1.in","r",stdin);
 68     //freopen("1.out","w",stdout);
 69     int cas=read();
 70     while(cas--)
 71     {
 72         int n=read(),q=read();
 73         rep(i,1,cnt) t[i].l=t[i].r=t[i].s=0;
 74         cnt=1; root[0]=1;
 75         rep(i,1,n)
 76         {
 77             int x=read();
 78             root[i]=root[i-1];
 79             update(1,1e6,x,root[i]);
 80         }
 81         int ans=0;
 82         rep(i,1,q)
 83         {
 84             int l=read(),r=read(),p=read(),k=read();
 85             l^=ans; r^=ans; p^=ans; k^=ans;
 86             int left=0,right=1e6;
 87             ans=1e6;
 88             while(left<=right)
 89             {
 90                 int mid=(left+right)>>1;
 91                 int x=max(1,p-mid),y=min(1000000,p+mid);
 92                 int t=query(1,1e6,x,y,root[l-1],root[r]);
 93                 if(t>=k){ans=mid; right=mid-1;}
 94                  else left=mid+1;
 95             }
 96             printf("%d\n",ans);
 97         }
 98     }
 99     return 0;
100 }