Just h-index+莫队+二分+树状数组

Just h-index

Problem Description

The h-index of an author is the largest h where he has at least h papers with citations not less than h.

Bobo has published n papers with citations a1,a2,…,an respectively.
One day, he raises q questions. The i-th question is described by two integers li and ri, asking the h-index of Bobo if has *only* published papers with citations ali,ali+1,…,ari.

Input

The input consists of several test cases and is terminated by end-of-file.

The first line of each test case contains two integers n and q.
The second line contains n integers a1,a2,…,an.
The i-th of last q lines contains two integers li and ri.

Output

For each question, print an integer which denotes the answer.

## Constraint

* 1≤n,q≤105
* 1≤ai≤n
* 1≤li≤ri≤n
* The sum of n does not exceed 250,000.
* The sum of q does not exceed 250,000.

Sample Input

5 3 1 5 3 2 1 1 3 2 4 1 5 5 1 1 2 3 4 5 1 5

Sample Output

2 2 2 3

Source

CCPC2018-湖南全国邀请赛-重现赛（感谢湘潭大学）

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#define happy  #include<bits/stdc++.h> using namespace std;  typedef long long ll; typedef long double ld;  typedef pair<int,int> pi; typedef pair<ll,ll> pl; typedef pair<ld,ld> pd;  typedef vector<int> vi; typedef vector<ld> vd; typedef vector<ll> vl; typedef vector<pi> vpi; typedef vector<pl> vpl;   #define rep(i,a,b) for(int i=a;i<=b;i++) #define per(i,a,b) for(int i=b-1;i>=a;i--)  #define all(a) (a).begin(),(a).end() #define sz(x) (int)(x).size() #define mp make_pair #define pb push_back #define eb emplace_back #define f first #define s second  ll rd(){     ll x=0,f=1;char ch=getchar();     while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}     while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();}     return x*f; }  const int MAXN=1e5+10;  int tree[MAXN]; int blocksize; int block[MAXN]; int ans[MAXN]; int a[MAXN],N,Q;  inline int lowbit(int x){     return x&-x; }   struct query{     int l,r,id; }q[MAXN];  bool cmp(query a,query b){     if(block[a.l]==block[b.l])         return a.r<b.r;     return block[a.l]<block[b.l]; } int tot;  void add(int x,int C){     for(int i=x;i<=MAXN;i+=lowbit(i)){         tree[i]+=C;     } }  int sum(int x){     int ans=0;     for(int i=x;i;i-=lowbit(i))         ans+=tree[i];     return ans; }  bool judge(int x){     if(tot-sum(x-1)>=x)         return true;     return false; }   void solve(){     int l=1,r=1;     tot=1;     add(a[1],1);     rep(i,0,Q-1){         while(q[i].r>r){r++;add(a[r],1);tot++;}         while(q[i].r<r){add(a[r],-1);r--;tot--;}         while(q[i].l<l){l--;add(a[l],1);tot++;}         while(q[i].l>l){add(a[l],-1);l++;tot--;}         int ll=1,rr=N;         int m;         while(ll<=rr){             m=(ll+rr)/2;             if(judge(m)){                 ll=m+1;             }else rr=m-1;         }         ans[q[i].id]=rr;     } }   int main(){ #ifdef happy     freopen("in.txt","r",stdin); #endif     while(~scanf("%d%d",&N,&Q)){         memset(tree,0,sizeof(tree));         blocksize=sqrt(N);         rep(i,1,N){             a[i]=rd();             block[i]=i/blocksize+1;         }         rep(i,0,Q-1){             q[i].l=rd();             q[i].r=rd();             q[i].id=i;         }         sort(q,q+Q,cmp);         solve();         rep(i,0,Q-1)         printf("%d\n",ans[i]);     } } 

文章来源: Just h-index+莫队+二分+树状数组