Submission #992876

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Source Code Expand

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

typedef pair<int, int> pii;
typedef long long ll;
typedef vector<int> vi;

#define pb push_back
#define eb emplace_back
#define mp make_pair
#define fi first
#define se second
#define rep(i,n) rep2(i,0,n)
#define rep2(i,m,n) for(int i=m;i<(n);i++)
#define ALL(c) (c).begin(),(c).end()

ll N, A;
ll ret;

int main() {
	cin >> N >> A;
	ret = N;

	for (ll i = 2; i <= 1000010; ++i) {
		ll u = 1;
		ll m = LLONG_MAX;
		ll c = 0;

		while (true) {
			u *= i;
			c += A + i;

			m = min(m, c + (N+u-1)/u);

			if (u >= N) break;
		}

		ret = min(ret, m);
	}

	for (ll i = 2; i <= min(1000010LL, N); ++i) {
		ll lo = 1, hi = N;
		while (hi-lo>1) {
			ll m=(lo+hi)/2;
			if ((N+m-1)/m>=i) {
				lo = m;
			} else hi = m;
		}
		//ret = min(ret, lo+A+i);
	}

	cout << ret << endl;

	return 0;
}

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