Submission #1036846

#	Time	Username	Problem	Language	Result	Execution time	Memory
1036846		ALeonidou	The Big Prize (IOI17_prize)	C++17	100 / 100	25 ms	596 KiB

prize

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

#define ll int
#define endl "\n"
#define sz(x) (ll)x.size()
#define F first
#define S second
#define pb push_back

typedef vector <ll> vi;
typedef pair <ll,ll> ii;
typedef vector <ii> vii;

#define dbg(x) cout<<#x<<": "<<x<<endl;
#define dbg2(x,y) cout<<#x<<": "<<x<<" "<<#y<<": "<<y<<endl;
#define dbg3(x,y,z) cout<<#x<<": "<<x<<" "<<#y<<": "<<y<<" "<<#z<<": "<<z<<endl;

void printVct(vi &v){
	for (ll i =0; i<sz(v); i++){
		cout<<v[i]<<" ";
	}
	cout<<endl;
}

ll common_val = 0;
ll ans = -1;

void query(ll q, vi &v, ll &s){
	v = ask(q);
	s = v[0] + v[1];
	if (s == 0){
		ans = q;
	}
}

void bs(ll l, ll r, ll x, ll belowL, ll aboveR){
	if (x == 0) return;
	if (l > r) return;
	if (ans != -1) return;

	ll mid = (l+r)/2;
	vi v; ll s;
	query(mid, v, s);
	if (ans != -1) return;

	if (s != common_val){
		ll l_mid = mid-1;
		ll c = 1;
		while (l_mid >= l && s != common_val){
			query(l_mid, v, s);	
			if (ans != -1) return;
			if (s == common_val) break;
			l_mid--;
			c++;
		}
		if (l_mid < l){
			ll val_r = x - c;
			bs(mid+1,r,val_r,c,aboveR);
		}
		else{
			ll val_l = v[0] - belowL;
			ll val_r = v[1] - aboveR - c;
			bs(l,mid-1,val_l,belowL,v[1]);
			bs(mid+1,r,val_r,v[0]+c,aboveR);
		}
	}
	else{
		ll val_l = v[0] - belowL;
		ll val_r = v[1] - aboveR;

		//hit on a common val:
		bs(l,mid-1,val_l,belowL,v[1]);
		bs(mid+1,r,val_r,v[0],aboveR);
	}
}

int find_best(int n) {	
	//n < 5000: BF - linear search
	if (n <= 5000){
		for (ll i =0; i<n; i++){	
			vi v = ask(i);
			ll s = v[0] + v[1];
			if (s == 0){
				return i;
			}
		}
	}

	//step 1: Find common value
	for (ll i =0; i<474; i++){
		vi v = ask(i);
		ll s = v[0] + v[1];
		common_val = max(common_val, s);
		if (s > 30){
			break;
		}
		if (s == 0){
			return i;
		}
	}

	// common_val = 4;

	//identify all uncommon one by one
	//start from pos = 0, and move like binary lifting
	bs(0, n-1, common_val, 0, 0);

	return ans;
}

/*
6
1 2 2 2 2 2
*/

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