Poj2104k-th Number (Chairman tree)

k-th number Time Limit: 20000MS Memory Limit: 65536K Total Submissions: 46886 Accepted: 15682 Case Time Limit: 2000MS Description You is working for Macrohard company in data Structures Department. After failing your previous task on key insertion you were asked to write a new data structure that would being able to re Turn quickly k-th order statistics in the array segment. That's, given an array A[1...N] of different integer numbers, your program must answer a series of questions Q (I, J, K) I n the form: "What would is the k-th number in A[I...J] segment, if this segment is sorted?" For example, consider the array a = (1, 5, 2, 6, 3, 7, 4). Let the question is Q (2, 5, 3). The segment a[2...5] is (5, 2, 6, 3). If We sort this segment, we get (2, 3, 5, 6), the third number was 5, and therefore the answer to the question is 5. Input The first line of the input file contains n---the size of the array, and M---the number of questions to answer (1 < = N <=, 1 <= m <= 5 000). The second line contains n different integer numbers not exceeding 109 by their absolute values---the array for which th E answers should be given. The following m lines contain question descriptions, each description consists of three numbers:i, J, and K (1 <= i &L T;= j <= N, 1 <= k <= j-i + 1) and represents the question Q (I, J, K). Output For each question output of the answer to it---the k-th number in sorted A[I...J] segment. Sample Input 7 31 5 2 6 3 7 42 5 34 4 11 7 3 Sample Output 563 Hint This problem have huge input,so please use C-style input (scanf,printf), or your may got time limit exceed. Source Northeastern Europe 2004, Northern subregion

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#include <stdio.h> #include <vector> #include <algorithm>using namespace std;const int maxn=1e5+5; struct node{int l,r;int sum;} T[maxn*40];int root[maxn],a[maxn],cnt,sum;vector<int>v;int getid (int x) {return lower_bound (V.begin (), V.end () , x)-v.begin () +1;} void update (int l,int r,int &x,int y,int pos) {t[++cnt]=t[y],t[cnt].sum++,x=cnt;if (l==r) return; int mid= (L+R)/2;if ( Mid>=pos) update (L,MID,T[X].L,T[Y].L,POS); else update (MID+1,R,T[X].R,T[Y].R,POS);} int query (int l,int r,int x,int y,int k) {if (l==r) return l;int mid= (l+r)/2;int sum=t[t[y].l].sum-t[t[x].l].sum;if (sum &GT;=K) return query (L,MID,T[X].L,T[Y].L,K), Else return query (mid+1,r,t[x].r,t[y].r,k-sum);} int main () {int n,m;scanf ("%d%d", &n,&m), for (int i=1;i<=n;i++) scanf ("%d", &a[i]), V.push_back (A[i]); Sort (V.begin (), V.end ()), V.erase (Unique (V.begin (), V.end ()), V.end ()), for (int i=1;i<=n;i++) update (1,n,root[i], Root[i-1],getid (A[i])); for (int i=0;i<m;i++) {int a,b,k;scanf ("%d%d", &a,&b,&k);p rintf ("%d\n", V[query (1,n,root[a-1],root[b],k)-1]);} return 0;}

Poj2104k-th Number (Chairman tree)