Submission #415161

#	Time	Username	Problem	Language	Result	Execution time	Memory
415161		Bill_00	The Big Prize (IOI17_prize)	C++14	0 / 100	3 ms	1856 KiB

prize

#include "prize.h"
#include <bits/stdc++.h>
using namespace std;
int l[200005],r[200005],answer=-1;
int sum[2000005],n;
void update(int id,int L,int R,int x){
	if(L==R){
		sum[id]=1;
		return;
	}
	int m=(L+R)>>1;
	if(x>=m) update(id*2,L,m,x);
	else update(id*2+1,m+1,R,x);
	sum[id]=sum[id*2]+sum[id*2+1];
}
int query(int id,int L,int R,int LL,int RR){
	if(RR<L || R<LL) return 0;
	if(LL<=L && R<=RR) return sum[id];
	int m=(L+R)>>1;
	return query(id*2,L,m,LL,RR)+query(id*2+1,m+1,R,LL,RR);
}
int find(int id,int L,int R,int x){
	if(L==R) return L;
	int m=(L+R)>>1;
	if(x<=sum[id*2]) return find(id*2,L,m,x);
	else return find(id*2+1,m+1,R,x-sum[id*2]);
}
void solve(int L,int R){
	if(answer!=-1) return;
	if(L+1>=R){
		return;
	}
	int m=(L+R)>>1;
	vector<int>res=ask(m);
	l[m]=res[0];
	r[m]=res[1];
	if(l[m]+r[m]==0){
		answer=m;
		return;
	}
	update(1,0,n-1,m);
	int y=query(1,0,n-1,0,m);
	int x=find(1,0,n-1,y-1);
	int z=find(1,0,n-1,y+1);
	if(l[m]!=l[x] || r[m]!=r[x]){
		solve(L,m);
	}
	if(answer!=-1) return;
	if(l[m]!=l[z] || r[m]!=r[z]){
		solve(m+1,R);
	}
}
int find_best(int N){
	// for(int i = 0; i < n; i++){
	// 	std::vector<int> res = ask(i);
	// 	if(res[0] + res[1] == 0)
	// 		return i;
	// }
	n=N;
	for(int i=0;i<n;i++){
		l[i]=r[i]=-1;
	}
	int m=(n-1)/2;
	vector<int>res=ask(0);
	l[0]=res[0];
	r[0]=res[1];
	if(l[0]+r[0]==0) return 0;
	update(1,0,n-1,0);
	res=ask(n-1);
	l[n-1]=res[0];
	r[n-1]=res[1];
	update(1,0,n-1,n-1);
	if(l[n-1]+r[n-1]==0) return n-1;
	solve(0,n-1);
	return answer;
}

Compilation message (stderr)

prize.cpp: In function 'int find_best(int)':
prize.cpp:63:6: warning: unused variable 'm' [-Wunused-variable]
   63 |  int m=(n-1)/2;
      |      ^

• Subtask 1: 0 / 20
• Subtask 2: 0 / 80