Submission #992966

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Source Code Expand

#include <iostream>
#include <cassert>
#include <cmath>
using namespace std;

long long LINF = (long long) 1e18;

long long mul(long long a, long long b) {
    if (b == 0 || a <= LINF / b) return a * b;
    return LINF;
}

long long power(long long a, long long n) {
    long long res = 1;
    for (int i = 0; i < n; ++i) {
        res = mul(res, a);
    }
    return res;
}

int main() {
    long long n; cin >> n;
    long long a; cin >> a;
    long long res = n;
    for (int foo = 2; ; ++foo) {
        long long x = pow(n, 1.0 / foo);
        //cout << foo << ' ' << x << ' ' << pow(n, 1.0 / foo) << endl;
        while (power(x + 1, foo) <= n) ++x;
        while (power(x, foo) > n) --x;
        if (x == 1) break;
        //cout << foo << ' ' << x << endl;
        assert(power(x, foo) <= n);
        for (int bar = 0; bar <= foo; ++bar) {
            if (mul(power(x, bar), power(x + 1, foo - bar)) >= n) {
                //cout << x << ' ' << bar << ' ' << foo - bar << endl;
                res = min(res, mul(x, bar) + mul(x + 1, foo - bar) + mul(foo - 1, a));
            }
        }
    }
    cout << res << endl;
    return 0;
}

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