Submission #255026

#	Time	Username	Problem	Language	Result	Execution time	Memory
255026		tinjyu	The Big Prize (IOI17_prize)	C++14	20 / 100	77 ms	2048 KiB

prize

#include "prize.h"
#include <bits/stdc++.h>
using namespace std;
int m,ball=0,a[200005][2],ans=-1;
int find(int x)
{
	if(a[x][0]==-1)
	{
		std::vector<int> res = ask(x);
		a[x][0]=res[0];
		a[x][1]=res[1];
	}
	return 0;
}
int solve(int s,int e){
	//cout<<s<<" "<<e<<endl;
	if(s>=e-1)return 0;
	if(ans!=-1)return 0;
	int ne,ns,c1=1,c2=1;
	ne=(s+e)/2,ns=(s+e)/2;
	while(ns<e)
	{
		find(ns);
		if(a[ns][0]+a[ns][1]==0)
		{
			ans=ns;
			return 0;
		}
		if(a[ns][0]+a[ns][1]!=ball)
		{
			if(a[ns][1]==0)
			{
				c1=0;
				break;
			}
			ns++;
		
		}
		else break;
	}
	while(s<ne)
	{
		find(ne);
		if(a[ne][0]+a[ne][1]==0)
		{
			ans=ne;
			break;
		}
		if(a[ne][0]+a[ne][1]!=ball)
		{
			if(a[ne][0]==0)
			{
				c2=0;
				break;
			}
			ne--;
			
		}
		else break;
	}
	//cout<<ne<<" "<<ns<<endl;
	if(c1==1 && a[ns][1]!=a[e][1])solve(ns,e);
	if(c2==1 && a[s][0]!=a[ne][0])solve(s,ne);

}
int find_best(int n) {
	for(int i=0;i<n;i++)
	{
		a[i][0]=-1;
		a[i][1]=-1;
	}
	for(int i=0;i<min(n,100);i++)find(i);
	for(int t = 0; t < 250; t++) {
		long long int i=rand();
		i%=n;
		find(i);
		//cout<<a[i][0]<<" "<<a[i][1]<<endl;
		if(a[i][0]+a[i][1]==0)
		{
			ans=i;
			break;
		}
		if(a[i][0] + a[i][1] > ball)
		{
			m=i;
			ball=a[i][0]+a[i][1];
		}
	}
	if(ans!=-1)return ans;
 
//	cout<<m<<endl;
	int start=0,end=n-1;
	while(true)
	{
		find(start);
		if(a[start][0]+a[start][1]==0)ans=start;
		if(a[start][0]+a[start][1]!=ball)start++;
		else break;
	}
	while(true)
	{
		find(end);
		if(a[end][0]+a[end][1]==0)ans=end;
		if(a[end][0]+a[end][1]!=ball)end--;
		else break;
	}
	if(ans!=-1)return ans;
	//cout<<start<<" "<<end<<endl;
	solve(start,m);
	solve(m,end);
	return ans;
}

Compilation message (stderr)

prize.cpp: In function 'int solve(int, int)':
prize.cpp:65:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^

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