Sorted Subsegments


Problem Statement :


Consider an array  of  integers. We perform  queries of the following type on :

Sort all the elements in the subsegment .
Given , can you find and print the value at index  (where ) after performing  queries?

Input Format

The first line contains three positive space-separated integers describing the respective values of  (the number of integers in ),  (the number of queries), and  (an index in ).
The next line contains  space-separated integers describing the respective values of .
Each line  of the  subsequent lines contain two space-separated integers describing the respective  and  values for query .

Output Format

Print a single integer denoting the value of  after processing all q  queries.



Solution :



title-img


                            Solution in C :

In  C  :





#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <string.h>
#include <math.h>
#include <stdlib.h>
#include <time.h>


struct Query{
	int l, r;
	int ignore;
};

int ar1[75000];
int ar2[75000];

struct Query queries[75000];
struct Query sarea[75000];


int cmp(const void *a, const void *b){
	return (*(int *)a - *(int *)b);
}

void insertionsort(int a[], int N){
	int i, j;
	int v;
	for (i = 1; i < N; i++){
		v = a[i];
		for (j = i; j>0 && a[j - 1] > v; j--){
			a[j] = a[j - 1];
		}
		a[j] = v;
	}
}

int main() {

	int n, q, k1, i, l, r, ign, j,mi,hr,nr,k,changed;
    int si, sj;
	int *a = ar1;
	int *b = ar2;

	scanf("%d %d %d", &n, &q, &k1);
	for (i = 0; i<n; i++){
		scanf("%d", &a[i]);
	}
	for (i = 0; i<q; i++){
		scanf("%d %d", &(queries[i].l), &(queries[i].r));
		queries[i].ignore = 0;
	}
	i = q ;
	do{
		i = i - 1;		
	} while (i >= 0 && (k1 < queries[i].l || k1 > queries[i].r));
	if (i >= 0){
		l = queries[i].l;
		r = queries[i].r;
		ign = i;
		for (i = i-1; i >= 0; i--){
			if (queries[i].r < l || queries[i].l > r){
				queries[i].ignore = 1;
			}
			else{
				if (queries[i].r > r && queries[i].l >= l)
					r = queries[i].r;
				else if (queries[i].l < l && queries[i].r <= r)
					l = queries[i].l;
				else  if (queries[i].l < l && queries[i].r > r){
					ign = i;
					r = queries[i].r;
					l = queries[i].l;
				}
			}
		}
		l = 0;
		r = 0;
        si = 0;
		for (i = 0; i <= ign; i++){

			if (!queries[i].ignore){
                for (sj = si - 1; sj >= 0; sj--){
					if (sarea[sj].l < queries[i].l && queries[i].l < sarea[sj].r) break;
					if (sarea[sj].l < queries[i].r && queries[i].r < sarea[sj].r) break;
   					if (sarea[sj].l >= queries[i].l && queries[i].r >= sarea[sj].r) break;
				}
				if (sj == -1){
					qsort(a + queries[i].l, queries[i].r - queries[i].l + 1, sizeof(int), cmp);
					sarea[si] = queries[i];
					si++;
				}
				else{
                    changed =0;
                    l = sarea[sj].l;
					r = sarea[sj].r;
					if (queries[i].l < l){
                        changed=1;
						hr = l - queries[i].l;
						memcpy(b, a + queries[i].l, hr*sizeof(int));
						//qsort(b, hr, sizeof(int), cmp);
                        insertionsort(b,hr);
						mi = 0;
						j = l;
						k = queries[i].l;
						nr = (r < queries[i].r ? r : queries[i].r);
						while (mi < hr && j <= nr)
						{
							a[k++] = (b[mi] < a[j] ? b[mi++] : a[j++]);
						}
						while (mi < hr) a[k++] = b[mi++];
						
					}
					if (queries[i].r > r){
                        changed+=2;
						hr = queries[i].r - r;
						memcpy(b, a + r + 1, hr*sizeof(int));
						//qsort(b, hr, sizeof(int), cmp);
                        insertionsort(b,hr);
						mi = hr - 1;
						j = r;
						k = queries[i].r;

						while (mi >= 0 && j >= queries[i].l)
						{
							a[k--] = (b[mi] > a[j] ? b[mi--] : a[j--]);
						}
						while (mi >= 0) a[k--] = b[mi--];
						r = queries[i].r;
					}
                    if (changed){
						sarea[sj].l = queries[i].l;
						sarea[sj].r = queries[i].r;
					}
				}
			}
		}
	}
	printf("%d", a[k1]);
	return 0;
}
                        


                        Solution in C++ :

In  C++  :






#include "bits/stdc++.h"
using namespace std;
#define rep(i,n) for(int (i)=0;(i)<(int)(n);++(i))
#define rer(i,l,u) for(int (i)=(int)(l);(i)<=(int)(u);++(i))
#define reu(i,l,u) for(int (i)=(int)(l);(i)<(int)(u);++(i))
static const int INF = 0x3f3f3f3f; static const long long INFL = 0x3f3f3f3f3f3f3f3fLL;
typedef vector<int> vi; typedef pair<int, int> pii; typedef vector<pair<int, int> > vpii; typedef long long ll;
template<typename T, typename U> static void amin(T &x, U y) { if(y < x) x = y; }
template<typename T, typename U> static void amax(T &x, U y) { if(x < y) x = y; }

typedef char Val;
struct Sum {
	int cnt;
	Sum() : cnt(0) {}
	Sum(const Val &val, int pos) : cnt(val) {}
	Sum &operator+=(const Sum &that) { cnt += that.cnt; return *this; }
	Sum operator+(const Sum &that) const { return Sum(*this) += that; }
};
struct Add {
	int assign;
	Add() : assign(-1) {}
	explicit Add(int a) : assign(a) {}
	Add &operator+=(const Add &that) {
		if(that.assign != -1)
			assign = that.assign;
		return *this;
	}
	void addToVal(Val &val, int pos) const {
		if(assign != -1)
			val = assign != 0;
	}
	void addToSum(Sum &sum, int left, int right) const {
		if(assign != -1)
			sum.cnt = assign != 0 ? right - left : 0;
	}
};

struct SegmentTree {
	vector<Val> leafs;
	vector<Sum> nodes;
	vector<Add> add;
	vector<int> leftpos, rightpos;
	int n, n2;
	void init(int n_, const Val &v = Val()) { init(vector<Val>(n_, v)); }
	void init(const vector<Val> &u) {
		n = 1; while(n < (int)u.size()) n *= 2;
		n2 = (n - 1) / 2 + 1;
		leafs = u; leafs.resize(n, Val());
		nodes.resize(n);
		for(int i = n - 1; i >= n2; -- i)
			nodes[i] = Sum(leafs[i * 2 - n], i * 2 - n) + Sum(leafs[i * 2 + 1 - n], i * 2 + 1 - n);
		for(int i = n2 - 1; i > 0; -- i)
			nodes[i] = nodes[i * 2] + nodes[i * 2 + 1];
		add.assign(n, Add());

		leftpos.resize(n); rightpos.resize(n);
		for(int i = n - 1; i >= n2; -- i) {
			leftpos[i] = i * 2 - n;
			rightpos[i] = (i * 2 + 1 - n) + 1;
		}
		for(int i = n2 - 1; i > 0; -- i) {
			leftpos[i] = leftpos[i * 2];
			rightpos[i] = rightpos[i * 2 + 1];
		}
	}
	Val get(int i) {
		int indices[128];
		int k = getIndices(indices, i, i + 1);
		propagateRange(indices, k);
		return leafs[i];
	}
	Sum getRangeCommutative(int i, int j) {
		int indices[128];
		int k = getIndices(indices, i, j);
		propagateRange(indices, k);
		Sum res = Sum();
		for(int l = i + n, r = j + n; l < r; l >>= 1, r >>= 1) {
			if(l & 1) res += sum(l ++);
			if(r & 1) res += sum(-- r);
		}
		return res;
	}
	Sum getRange(int i, int j) {
		int indices[128];
		int k = getIndices(indices, i, j);
		propagateRange(indices, k);
		Sum res = Sum();
		for(; i && i + (i&-i) <= j; i += i&-i)
			res += sum((n + i) / (i&-i));
		for(k = 0; i < j; j -= j&-j)
			indices[k ++] = (n + j) / (j&-j) - 1;
		while(-- k >= 0) res += sum(indices[k]);
		return res;
	}
	void set(int i, const Val &x) {
		int indices[128];
		int k = getIndices(indices, i, i + 1);
		propagateRange(indices, k);
		leafs[i] = x;
		mergeRange(indices, k);
	}
	void addToRange(int i, int j, const Add &x) {
		if(i >= j) return;
		int indices[128];
		int k = getIndices(indices, i, j);
		propagateRange(indices, k);
		int l = i + n, r = j + n;
		if(l & 1) { int p = (l ++) - n; x.addToVal(leafs[p], p); }
		if(r & 1) { int p = (-- r) - n; x.addToVal(leafs[p], p); }
		for(l >>= 1, r >>= 1; l < r; l >>= 1, r >>= 1) {
			if(l & 1) add[l ++] += x;
			if(r & 1) add[-- r] += x;
		}
		mergeRange(indices, k);
	}
private:
	int getIndices(int indices[], int i, int j) const {
		int k = 0, l, r;
		if(i >= j) return 0;
		for(l = (n + i) >> 1, r = (n + j - 1) >> 1; l != r; l >>= 1, r >>= 1) {
			indices[k ++] = l;
			indices[k ++] = r;
		}
		for(; l; l >>= 1) indices[k ++] = l;
		return k;
	}
	void propagateRange(int indices[], int k) {
		for(int i = k - 1; i >= 0; -- i)
			propagate(indices[i]);
	}
	void mergeRange(int indices[], int k) {
		for(int i = 0; i < k; ++ i)
			merge(indices[i]);
	}
	inline void propagate(int i) {
		if(i >= n) return;
		add[i].addToSum(nodes[i], leftpos[i], rightpos[i]);
		if(i * 2 < n) {
			add[i * 2] += add[i];
			add[i * 2 + 1] += add[i];
		} else {
			add[i].addToVal(leafs[i * 2 - n], i * 2 - n);
			add[i].addToVal(leafs[i * 2 + 1 - n], i * 2 + 1 - n);
		}
		add[i] = Add();
	}
	inline void merge(int i) {
		if(i >= n) return;
		nodes[i] = sum(i * 2) + sum(i * 2 + 1);
	}
	inline Sum sum(int i) {
		propagate(i);
		return i < n ? nodes[i] : Sum(leafs[i - n], i - n);
	}
};

int main() {
	int n; int q; int k;
	while(~scanf("%d%d%d", &n, &q, &k)) {
		vector<int> A(n);
		for(int i = 0; i < n; ++ i)
			scanf("%d", &A[i]);
		vector<int> l(q), r(q);
		for(int i = 0; i < q; ++ i)
			scanf("%d%d", &l[i], &r[i]), ++ r[i];
		vi values = A;
		sort(values.begin(), values.end());
		values.erase(unique(values.begin(), values.end()), values.end());
		int lo = 0, up = (int)values.size() - 1;
		while(up - lo > 0) {
			int mid = (lo + up + 1) / 2;
			vector<Val> initvals(n);
			rep(i, n)
				initvals[i] = values[mid] <= A[i];
			SegmentTree segt; segt.init(initvals);
			rep(i, q) {
				int cnt0 = r[i] - l[i] - segt.getRangeCommutative(l[i], r[i]).cnt;
				segt.addToRange(l[i], l[i] + cnt0, Add(0));
				segt.addToRange(l[i] + cnt0, r[i], Add(1));
			}
			if(segt.get(k))
				lo = mid;
			else
				up = mid - 1;
		}
		printf("%d\n", values[lo]);
	}
	return 0;
}
                    


                        Solution in Java :

In  Java :





import java.io.*;
import java.util.*;

public class Solution {
  private static InputReader in;
  private static PrintWriter out;
  
  public static int[] brr;
  
  static class SegmentTree {
    public SegmentTree left, right;
    public int nones, start, end;
    public int pushval;
    
    public SegmentTree(int start, int end) {
      this.start = start;
      this.end = end;
      this.pushval = -1;
      if (start != end) {
        int mid = (start + end) >> 1;
        left = new SegmentTree(start, mid);
        right = new SegmentTree(mid+1, end);
        nones = left.nones + right.nones;
      } else {
        nones = brr[start] == 1 ? 1 : 0;
      }
    }
    
    public int size() {
      return end-start+1;
    }
    
    public void push() {
      if (left == null) return;
      if (pushval == -1) return;
      left.nones = pushval == 1 ? left.size() : 0;
      left.pushval = pushval;
      right.nones = pushval == 1 ? right.size() : 0;
      right.pushval = pushval;
      pushval = -1;
    }
    public void join() {
      if (left == null) return;
      this.nones = left.nones+right.nones;
    }
    
    public int count(int s, int e) {
      if (start == s && end == e) return nones;
      push();
      int mid = (start + end) >> 1;
      if (mid >= e) return left.count(s, e);
      else if (mid < s) return right.count(s,e);
      else return left.count(s,mid)+right.count(mid+1,e);
    }
    
    public void set(int s, int e, int val) {
      if (s > e) return;
      if (start == s && end == e) {
        this.pushval = val;
        this.nones = val == 1 ? this.size() : 0;
        return;
      }
      push();
      int mid = (start+end) >> 1;
      if (mid >= e) {left.set(s, e, val);}
      else if (mid < s) {right.set(s,e,val);}
      else {
        left.set(s,mid,val);
        right.set(mid+1,e,val);
      }
      join();
    }
  }

  public static void main(String[] args) throws IOException {
    in = new InputReader(System.in);
    out = new PrintWriter(System.out, true);

    int n = in.nextInt(), q = in.nextInt(), k = in.nextInt();
    int[] arr = new int[n];
    for (int i = 0; i < n; i++) {
      arr[i] = in.nextInt();
    }
    HashSet<Integer> dis = new HashSet<>();
    for (int i = 0; i < n; i++) {
      dis.add(arr[i]);
    }
    ArrayList<Integer> ls = new ArrayList<>(dis);
    Collections.sort(ls);
    
    int[] l = new int[q];
    int[] r = new int[q];
    for (int i = 0; i < q; i++) {
      l[i] = in.nextInt();
      r[i] = in.nextInt();
    }
    
    int lo = 0, hi = ls.size()-1;
    while(lo<hi) {
      int mid = (lo+hi+1) >> 1;
      brr = new int[n];
      for (int i = 0; i < n; i++) {
        brr[i] = arr[i] < ls.get(mid) ? 0 : 1;
      }
      SegmentTree root = new SegmentTree(0, n-1);
      for (int i = 0; i < q; i++) {
        int a = root.count(l[i], r[i]);
        root.set(l[i], r[i], 0);
        root.set(r[i]-a+1, r[i], 1);
      }
      int x = root.count(k, k);
      if (x == 1) {
        lo = mid;
      } else {
        hi = mid-1;
      }
    }
    
    out.println(ls.get(lo));
    out.close();
    System.exit(0);
  }

  static class InputReader {
    public BufferedReader reader;
    public StringTokenizer tokenizer;

    public InputReader(InputStream stream) {
      reader = new BufferedReader(new InputStreamReader(stream), 32768);
      tokenizer = null;
    }

    public String next() {
      while (tokenizer == null || !tokenizer.hasMoreTokens()) {
        try {
          tokenizer = new StringTokenizer(reader.readLine());
        } catch (IOException e) {
          throw new RuntimeException(e);
        }
      }
      return tokenizer.nextToken();
    }

    public int nextInt() {
      return Integer.parseInt(next());
    }
  }


}
                    


                        Solution in Python : 
                            
In  Python3 :







import sys

##### Read Data
dat = [x.split() for x in sys.stdin.readlines()]
N = int(dat[0][0])
Q = int(dat[0][1])
k = int(dat[0][2])
a = list(map(int, dat[1]))
q = [list(map(int, x)) for x in dat[2:len(dat)]]

##### Process Queries
b = sorted(a)
lmin, rmax, pmax, qmin = (N-1), 0, 0, (N-1)    
pmin, qmax, flag = (N-1), 0, 1
count, span_q, ladder, revlad = [], 0, 0, 0
if Q >= 2:
    ladder = all(q[i+1][0] > q[i][0] for i in range(Q-1)) 
    revlad = all(q[i+1][1] < q[i][1] for i in range(Q-1))

if a != b and ladder < 1 and revlad < 1:
    for i in range(Q):
        l, r = q[i][0], q[i][1]       
        
        if (r-l) > (rmax-lmin):
            lmin, rmax = l, r	
        
        if l < pmin:
            pmin, pmax = l, r
        elif l == pmin and pmax < r:
            pmax = r
            
        if r > qmax:
            qmin, qmax = l, r
        elif r == qmax and qmin > l:
            qmin = l
    
    for i in range(Q):
        l, r = q[i][0], q[i][1]
        
        if l > lmin and r < rmax: continue     
        if l > pmin and r < pmax: continue             
        if l > qmin and r < qmax: continue        
        
        if i < (Q-1):
            if l >= q[i+1][0] and r <= q[i+1][1]:
                continue
            
        if i > 0:
            if l >= q[i-flag][0] and r <= q[i-flag][1]:
                flag += 1
                continue
            else:
                flag = 1

        count += [i]
        span_q += r-l+1

# Perform Queries 
if ladder > 0:
    l, r, Qu = q[0][0], q[0][1], int((k+5)/5)
    a[l:r+1] = sorted(a[l:r+1])
    for i in range(1, Q):
        l, r, r0, m, sig = q[i][0], q[i][1], q[i-1][1], 0, 0
        if l > r0 or (r-r0) > 0.1*(r0-l):
            a[l:r+1] = sorted(a[l:r+1])
            continue
        if k < l: break
        count = list(range(r0+1, r+1))
        for j in range(len(count)):
            p, new_A = count[j], a[count[j]]
            l, r0 = q[i][0], q[i-1][1]
            if a[l] >= new_A:
                del(a[p]); a[l:l] = [new_A]; continue
            elif a[r0+j-1] <= new_A:
                del(a[p]); a[r0+j:r0+j] = [new_A]; continue   
            while sig < 1:
                m = int((l+r0)/2)
                if a[m] > new_A:
                    r0 = m
                elif a[m+1] < new_A:
                    l = m+1
                else:
                    del(a[p]); a[m+1:m+1] = [new_A]                
                    sig = 1

elif revlad > 0:
    l, r, Qu = q[0][0], q[0][1], int((k+5)/5)
    a[l:r+1] = sorted(a[l:r+1])
    for i in range(1, Q):
        l, r, l0, m, sig = q[i][0], q[i][1], q[i-1][0], 0, 0
        if k > r: break
        if r < l0:
            a[l:r+1] = sorted(a[l:r+1]); continue        
        count = list(range(l, l0))
        for j in range(len(count)):
            p, new_A = count[j], a[count[j]]
            if a[l0] >= new_A:
                del(a[p]); a[l0:l0] = [new_A]; continue
            elif a[r] <= new_A:
                del(a[p]); a[r:r] = [new_A]; continue   
            while sig < 1:
                m = int((l0+r)/2)
                if a[m] > new_A:
                    r = m
                elif a[m+1] < new_A:
                    l0 = m+1
                else:
                    del(a[p]); a[m+1:m+1] = [new_A]                
                    sig = 1
    
elif span_q < 1e9 and a != b:
    for i in count:
        l, r = q[i][0], q[i][1]
        a[l:(r+1)] = sorted(a[l:(r+1)])
else:
    a[pmin:qmax+1] = sorted(a[pmin:qmax+1])   
print(a[k])
                    


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