Submission #302172

#	Time	Username	Problem	Language	Result	Execution time	Memory
302172		TMJN	The Big Prize (IOI17_prize)	C++17	0 / 100	2 ms	1948 KiB

prize

#include "prize.h"
#include <bits/stdc++.h>
using namespace std;

int L[200000],R[200000],tree[1<<19];

void update(int x){
	x+=1<<18;
	while(x){
		tree[x]++;
		x/=2;
	}
}

int calc(int l,int r){
	l+=1<<18;
	r+=1<<18;
	int a=0;
	while(l<r){
		if(l&1)a+=tree[l];
		if(~r&1)a+=tree[r];
		l=(l+1)/2;
		r=(r-1)/2;
	}
	if(l==r)a+=tree[l];
	return a;
}

int find_best(int n){
	for(int i=0;i<n;i++){
		L[i]=R[i]=-1;
	}
	int s;
	for(int i=0;i<n;i++){
		vector<int>v=ask(i);
		L[i]=v[0];
		R[i]=v[1];
		if((v[0]+v[1])*2<n){
			s=(v[0]+v[1]);
			break;
		}
	}
	for(int i=0;i<s;i++){
		int l=-1;
		int r=n-1;
		while(l+1!=r){
			int m=(l+r)/2;
			if(L[m]==-1){
				vector<int>v=ask(m);
				L[m]=v[0];
				R[m]=v[1];
			}
			if(L[m]+R[m]!=s){
				r=m;
			}
			else if(L[m]-calc(0,m)>0){
				r=m;
			}
			else{
				l=m;
			}
		}
		if(L[r]==-1){
			vector<int>v=ask(r);
			L[r]=v[0];
			R[r]=v[1];
		}
		update(r);
		if(L[r]==0&&R[r]==0){
			return r;
		}
	}
	return -1;
}

Compilation message (stderr)

prize.cpp: In function 'int find_best(int)':
prize.cpp:43:15: warning: 's' may be used uninitialized in this function [-Wmaybe-uninitialized]
   43 |  for(int i=0;i<s;i++){
      |              ~^~

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