Submission #794810

#	Time	Username	Problem	Language	Result	Execution time	Memory
794810		fatemetmhr	The Big Prize (IOI17_prize)	C++17	98.23 / 100	44 ms	2980 KiB

prize

//  ~ Be Name Khoda ~  //
 
#include "prize.h"
#include <bits/stdc++.h>
//#pragma GCC optimize ("O3")
//#pragma GCC target("avx2")
//#pragma GCC optimize("unroll-loops,Ofast")
 
using namespace std;
 
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
 
 
typedef long long ll;
 
#define pb       push_back
#define mp       make_pair
#define all(x)   x.begin(), x.end()
#define fi       first
#define se       second
 
const int maxn  =  1e6   + 10;
const int maxn5 =  5e5   + 10;
const int maxnt =  1.2e6 + 10;
const int maxn3 =  1e3   + 10;
const int mod   =  1e9   + 7;
const ll  inf   =  1e18;
 
 
pair <int, int> ans[maxn5];
bool mark[maxn5];
int mx = 0, done = 0, dim = -1, cnt = 0, per[maxn5];
 
 
 
pair <int, int> assk(int id){
	if(cnt > 10000)
		exit(0);
	if(!mark[id]){
		vector <int> x = ask(id);
		cnt++;
		mark[id] = true;
		ans[id].fi = x[0];
		ans[id].se = x[1];
	}
	mx = max(mx, ans[id].fi + ans[id].se);
	if(ans[id].fi + ans[id].se == 0)
		dim = id;
	return ans[id];
}
 
/*
int check(int l, int r){
	l = lower_bound(all(good), l) - good.begin();
	r = lower_bound(all(good), r) - good.begin();
	return r - l;
}
*/
 
void solve(int l, int r, int x){
	if(dim != -1 || x == 0 || r <= l)
		return;
	if(r - l <= 2 * x){
		done += x;
		int found = 0;
		for(int i = l; i < r; i++)
			per[i] = i;
		shuffle(per + l, per + r, rng);
		for(int i = l; i < r && found < x; i++){
			assk(per[i]);
			if(ans[per[i]].fi + ans[per[i]].se != mx)
				found++;
			if(dim != -1)
				return;
		}
		return;
	}
	/*
	int w = check(l, r);
	if(w != x){
		cout << l << ' ' << r << ' ' << x << ' ' << w << ' ' << endl;
		exit(0);
	}
	*/
	int mid = (l + r) >> 1;
	int ptl = mid, ptr = mid + 1;
	mid = -1;
	int found = 0;
	//cout << "entering " << l << ' ' << r << ' ' << x << ' ' << cnt << ' ' << done << ' ' << dim << endl;
	while((ptl >= l || ptr < r) && found < x){
		////cout << "now " << ptl << ' ' << ptr << endl;
		if(ptl >= l){
			assk(ptl);
			if(dim != -1)
				return;
			if(ans[ptl].fi + ans[ptl].se == mx){
				ptr--;
				mid = ptl;
				break;
			}
			else
				found++;
		}
		if(found == x)
			break;
		if(ptr < r){
			assk(ptr);
			if(dim != -1)
				return;
			if(ans[ptr].fi + ans[ptr].se == mx){
				ptl = max(ptl, l);
				mid = ptr;
				break;
			}
			else
				found++;
		}
		if(ptl >= l)
			ptl--;
		if(ptr < r)
			ptr++;
	}
	//cout << "done with " << cnt << ' ' << done << ' ' << found << endl;
	//cout << "solving " << l << ' ' << r << ' ' << x << ' ' << found << ' ' << ptl << ' ' << ptr << ' ' << mid << ' ' << ans[mid].fi << endl;
	if(found == x){
		done += found;
		for(int i = l; i < r; i++) if(mark[i] && ans[i].fi + ans[i].se == 0)
			dim = i;
		return;
	}
	//if(mid == -1){
	//	cout << l << ' ' << r << ' ' << x << ' ' << found << ' ' << done << ' ' << ptl << ' ' << ptr << endl;
	//}
	assert(mid != -1);
	int keep = 0, keepdone = done;
	if(ptl > l){
		int lef = ans[mid].fi - done;
		for(int i = ptl; i < mid; i++) if(mark[i] && ans[i].fi + ans[i].se != mx)
			lef--;
		keep = lef;
		solve(l, ptl, lef);
		if(dim != -1)
			return;
	}
	if(ptr + 1 < r){
		int rig = x - keep;
		for(int i = ptl; i <= min(r - 1, ptr); i++) if(mark[i] && ans[i].fi + ans[i].se != mx){
			rig--;
			done++;
		}
		//if(rig < 0){
		//	cout << "WAAA " << rig << ' ' << l << ' ' << r << ' ' << ptl << ' ' << mid << ' ' << ptr << ' ' << x << ' ' << keep << ' ' << keepdone << ' ' << ans[mid].fi << endl;
		//}
		//cout << "in " << rig << endl;
		solve(ptr + 1, r, rig);
 
	}
 
}
 
int find_best(int n){
	//*
	int tt = 450;
	while(tt--)
		assk(rng() % n);
	//*/
	//mx = 1;
	if(dim != -1)
		return dim;
	solve(0, n, mx);
	//assert(dim != -1);
	//cout << cnt << endl;
	return dim;
}
 
 
 
 

Compilation message (stderr)

prize.cpp: In function 'void solve(int, int, int)':
prize.cpp:135:16: warning: unused variable 'keepdone' [-Wunused-variable]
  135 |  int keep = 0, keepdone = done;
      |                ^~~~~~~~

• Subtask 1: 20 / 20
• Subtask 2: 78.23 / 80