Submission #431434

#	Time	Username	Problem	Language	Result	Execution time	Memory
431434		Belgutei	The Big Prize (IOI17_prize)	C++17	20 / 100	154 ms	1072 KiB

prize

#include "prize.h"
#include<bits/stdc++.h>

using namespace std;

#define ll long long
#define ff first
#define ss second
#define pb push_back
#define mk make_pair

vector<int> v; 
map<int,pair<int,int> > mp;
bool check[200005];
int ans,mx,N;

int solve(int k){
	for(int i=0; i<k; i++){
		vector<int> vv;
		vv=ask(i);
		if(vv[0]==0 && vv[1]==0){
			return i;
		}
	}
	return 0;
}

void dfs(int x, int y){
	if(x>y) return;
	int a,b,c,d;
	if(check[x]==1){
		a=mp[x].ff;
		b=mp[x].ss;
	}
	else{
		vector<int> v1=ask(x);
		a=v1[0];
		b=v1[1];
		check[x]=1;
		mp[x].ff=a;
		mp[x].ss=b;
	}
	if(x==y){
		if(a+b!=mx) v.pb(x);
		return;
	}
	if(check[y]==1){
		c=mp[y].ff;
		d=mp[y].ss;
	}
	else{
		vector<int> v2=ask(y);
		c=v2[0];
		d=v2[1];
		mp[y].ff=c;
		mp[y].ss=d;
		check[y]=1;
	}
	if(a+b==mx && c+d==mx){
		if(c-a==0 || y-x==1) return;
		int mid=(x+y)/2;
		dfs(x,mid);
		dfs(mid+1,y);
	}
	else{
		if(a+b<mx && c+d<mx){
			v.pb(x);
			v.pb(y);
			if(y-x>=2){
				int mid=((y-1)+(x+1)/2);
				if(mid<N) dfs(x+1,mid);
				dfs(mid+1,y-1);
			}
			return;
		}
		if(a+b<mx){
			v.pb(x);
			if(x+1!=y){
				int mid=(x+1+y)/2;
				if(mid<N) dfs(x+1,mid);
				dfs(mid+1,y);
			}
			return;
		}
		v.pb(y);
		if(x!=y-1){
			int mid=(x-1+y)/2;
			if(mid<N) dfs(x,mid);
			dfs(mid+1,y-1);
		}
	}
}

int find_best(int n) {
	N=n;
	if(n<=4000){
		return solve(n);
	}
	for(int i=0; i<min(500,n); i++){
		vector<int> vv;
		vv=ask(i);
		check[i]=1;
		mp[i].ff=vv[0];
		mp[i].ss=vv[1];
		mx=max(mx,vv[0]+vv[1]);
	}
	int l=0;
	int r=n-1;
	dfs(l,r);
	for(int i=0; i<v.size(); i++){
		vector<int> vv;
		vv=ask(v[i]);
		if(vv[0]==0 && vv[1]==0){
			return v[i];
		}
	}
	return ans;
}

Compilation message (stderr)

prize.cpp: In function 'int find_best(int)':
prize.cpp:110:16: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  110 |  for(int i=0; i<v.size(); i++){
      |               ~^~~~~~~~~

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