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  1. #include <bits/stdc++.h>
  2. #define ll long long int
  3. using namespace std;
  4.  
  5. // l^(1/k) < x < r ^ (1/k)
  6. ll find(ll l, ll r){
  7.     ll re = 1;
  8.     ll le = 1, ri = r+1;
  9.     while(le<ri){
  10.         ll k = (le+ri)/2;
  11.         ll low = ceil(pow(l, 1.0 / k));
  12.         ll high = floor(pow(r, 1.0 / k));
  13.         if(low<=high){
  14.             //cout<<"find11111 l:" << le << " r:"<<ri << " low:"<<low<< " high:"<<high<< " k:"<<k <<"\n";
  15.             re = k;
  16.             le=k+1;
  17.         } else {
  18.             //cout<<"find22222 l:" << le << " r:"<<ri << " low:"<<low<< " high:"<<high<< " k:"<<k <<"\n";
  19.             ri=k;
  20.         }
  21.     }
  22.  
  23.     return re;
  24. }
  25.  
  26. ll find2(ll num){
  27.     ll re = 1;
  28.     for(ll i=2;i<=(ll) sqrt(num);i++){
  29.        float logaric = log(num)/log(i); 
  30.     //   cout<< i << "  logaric " << logaric << " (ll)logaric " << (ll)logaric << endl;
  31.        if(logaric -  (ll)logaric ==0){
  32.         //   cout<< "----------- " << logaric << endl;
  33.            re = logaric;
  34.            return re;
  35.        }
  36.     }
  37.  
  38.     return re;
  39. }
  40.  
  41. int main()
  42. {
  43.  
  44.     ll t;
  45.     cin>>t;
  46.     for(int i=1;i<=t;i++){
  47.         ll l,r;
  48.         cin>>l>>r;
  49.         ll re = 1;
  50.         if(l==r) re = find2(l);
  51.         else re = find(l,r);
  52.         cout<<"Case #"<<i<<": "<<re;
  53.         if(i!=t)cout<<"\n";
  54.     }
  55.  
  56.     return 0;
  57. }
Success #stdin #stdout 0.01s 5288KB
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Case #1: 6
https://ideone.com/4otmQv
language:
C++14 (gcc 8.3)
created:
11 days ago
visibility:
public

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