Submission #1832878

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Source Code Expand

#include <bits/stdc++.h>

#define fr first
#define sc second
#define OK puts("OK");
#define pb push_back
#define mk make_pair

using namespace std;

typedef long long ll;

const ll inf = (ll)1e18 + 7;
const int N = (int)2e6 + 7;

ll n,a;
ll mn = inf;

ll bpow (ll x,ll o) {
        ll res = 1;
        for (int i = 1; i <= o; i ++) {
                res = res * 1ll * x;
        }
        return res;
}
bool check (ll x,int o) {
        for (int i = 1; i <= o + 1; i ++) {
                if (bpow(x,i) * 1ll * bpow(x - 1,(o + 1 - i)) >= n)
                        return true;
        }
        return false;
}
 main () {
        cin >> n >> a;

        for (int i = 0; i <= 40; i ++) {
                ll l = 1,r = n;

                while (r - l > 1) {
                        ll m = (r + l) >> 1;

                        if (check(m,i))
                                r = m;
                        else
                                l = m;
                }
                for (int j = 1; j <= i + 1; j ++) {
                        if (bpow(r,j) * bpow(r - 1,(i + 1 - j)) >= n) {
                                mn = min(mn,i * 1ll * a + j * 1ll * r + (r - 1) * 1ll * (i + 1 - j));
                                break;
                        }
                }
        }
        cout << mn << endl;
}

Submission Info

Judge Result