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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3. #define FAST ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
  4. typedef long long ll;
  5.  
  6.  
  7. set<ll> lucky_nums;
  8. void generate_lucky(ll number,ll x,ll y,ll n){
  9.  
  10.     if(number > n) return;
  11.  
  12.     if(number>0){
  13.         lucky_nums.insert(number);
  14.     }
  15.  
  16.     long long a = number * 10 + x;
  17.     long long b = number * 10 + y;
  18.  
  19.     if(a != number && a <= n)
  20.         generate_lucky(a,x,y,n);
  21.  
  22.     if(b != number && b <= n)
  23.         generate_lucky(b,x,y,n);
  24.  
  25. };
  26.  
  27.  
  28. int main() {
  29.     FAST
  30.     ll n;
  31.     cin >> n;
  32.     for(int x = 0;x<10;x++){
  33.         for(int y = x; y<10;y++){
  34.             generate_lucky(0, x, y, n);
  35.         }
  36.     }
  37.  
  38.     cout << lucky_nums.size() << "\n";
  39.     // system("pause");
  40.     return 0;
  41. }
Success #stdin #stdout 0.39s 63068KB
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https://ideone.com/Sz1Wg5
language:
C++14 (gcc 8.3)
created:
2 hours ago
visibility:
public

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