Submission #436313

#	Time	Username	Problem	Language	Result	Execution time	Memory
436313		frodakcin	Packing Biscuits (IOI20_biscuits)	C++17	100 / 100	171 ms	1328 KiB

biscuits

#include "biscuits.h"
#include <cstdio>

using ll = long long;

ll x;
std::vector<ll> a;

bool test(ll v) // O(K)
{
	ll n=0;
	for(int i=0;v;v>>=1, n>>=1, ++i)
	{
		if(i<(int)a.size()) n+=a[i];
		if(v&1)
			if((n-=x)<0)
				return 0;
	}
	return 1;
}

ll get(int b) // O(K^2) -- max, with b'th bit turned on
{
	ll v=1ll<<b;
	for(int i=b-1;i>=0;--i)
		if(test(v|1ll<<i))
			v|=1ll<<i;
	return v;
}

const int MX = 2e5; // idk, just smth large
ll stv[MX];
int l[MX], r[MX], X;

int nn(int p=0)
{
	++X;
	stv[X]=stv[p];
	l[X]=l[p];
	r[X]=r[p];
	return X;
}

void up(int n) // do NOT call on leaves
{
	stv[n]=stv[l[n]]+stv[r[n]];
}

int pull(int n, ll nl, ll nr, ll ql, ll qr)
{
	if(ql <= nl && nr <= qr) return n;
	if(nr-nl>1)
	{
		n = nn(n);
		ll m=nl+(nr-nl)/2;
		if(ql < m) l[n] = pull(l[n], nl, m, ql, qr); else l[n]=0;
		if(m < qr) r[n] = pull(r[n], m, nr, ql, qr); else r[n]=0;
		up(n);
	}
	return n;
}

long long count_tastiness(long long _x, std::vector<long long> _a)
{
	x=_x;
	a=_a;

	X=0;
	int root=nn();
	stv[root]=1;

	for(int i=0;;++i)
	{
		int nroot = nn();
		l[nroot] = root;
		r[nroot] = 0;

		if(test(1ll<<i))
		{
			ll bound = get(i);
			bound ^= 1ll<<i;
			r[nroot] = pull(root, 0, 1ll<<i, 0, bound+1);
			//printf("%d: %lld [%lld]\n", i, bound+1, stv[r[nroot]]);
		}
		else if(i>=(int)a.size()) break;

		root = nroot;
		up(root);
		//printf("%d: %lld\n", i, stv[root]);
	}
	return stv[root];
}

• Subtask 1: 9 / 9
• Subtask 2: 12 / 12
• Subtask 3: 21 / 21
• Subtask 4: 35 / 35
• Subtask 5: 23 / 23