Submission #6879787

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Source Code Expand

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

typedef long long ll;
typedef unsigned long long ull;
typedef pair<ll, ll> P;

#define fi first
#define se second
#define repl(i,a,b) for(ll i=(ll)(a);i<(ll)(b);i++)
#define rep(i,n) repl(i,0,n)
#define all(x) (x).begin(),(x).end()
#define dbg(x) cout<<#x"="<<x<<endl
#define mmax(x,y) (x>y?x:y)
#define mmin(x,y) (x<y?x:y)
#define maxch(x,y) x=mmax(x,y)
#define minch(x,y) x=mmin(x,y)
#define uni(x) x.erase(unique(all(x)),x.end())
#define exist(x,y) (find(all(x),y)!=x.end())
#define bcnt __builtin_popcountll

#define INF 1e12
#define mod 1000000007

ll N,A;

int main(){
  cin.tie(0);
  ios::sync_with_stdio(false);

  cin>>N>>A;
  ll res=N;
  repl(C,1,41){
    ll lb=1,ub=INF;
    while(ub-lb>1){
      ll r=(lb+ub)/2;
      ll tmp=r;
      rep(i,C){
        if(tmp>INF/r) tmp=INF;
        else tmp*=r;
      }
      if(tmp>=N) ub=r;
      else lb=r;
    }
    {
      ll r=ub;
      ll v=1;
      rep(i,C)v*=r;
      minch(res,C*(r+A)+(N+v-1)/v);
    }
    if(ub>2){
      ll r=ub-1;
      ll v=1;
      rep(i,C)v*=r;
      minch(res,C*(r+A)+(N+v-1)/v);
    }
  }
  cout<<res<<endl;

  return 0;
}

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