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  1. #include <bits/stdc++.h>
  2. #define FNAME ""
  3. using namespace std;
  4. const int MAXN = 501;
  5. typedef long long ll;
  6. const ll MOD = 1e9 + 7;
  7.  
  8. void fastip() {
  9.     ios_base::sync_with_stdio(0);
  10.     cin.tie(0); cout.tie(0);
  11.     if (fopen(FNAME".inp", "r")) {
  12.         freopen(FNAME".inp", "r", stdin);
  13.         freopen(FNAME".out", "w", stdout);
  14.     }
  15. }
  16.  
  17. vector<string> beautiful_number;
  18. vector<long long> correct_number;
  19. string s = "";
  20. long long n;
  21.  
  22. void init(){
  23.     beautiful_number.push_back("1");
  24.     beautiful_number.push_back("22");
  25.     beautiful_number.push_back("333");
  26.     beautiful_number.push_back("4444");
  27.     beautiful_number.push_back("55555");
  28.     beautiful_number.push_back("666666");
  29.     beautiful_number.push_back("7777777");
  30.     beautiful_number.push_back("88888888");
  31.     beautiful_number.push_back("999999999");    
  32. }
  33.  
  34. void backtrack(int i,int sum){
  35.     if(sum + i + 1 > 10){
  36.         return;
  37.     }
  38.     for(int j = i ; j < 9 ; j++){
  39.         if(sum + j + 1 <= 10){
  40.             string tmp = s;
  41.             s += beautiful_number[j];
  42.             string k = s;
  43.             beautiful_number.push_back(k);
  44.             while(next_permutation(k.begin(),k.end())){
  45.                 beautiful_number.push_back(k);
  46.             }
  47.             backtrack(j + 1, sum + j + 1);
  48.             s = tmp;
  49.         }
  50.     }
  51. }
  52.  
  53. int main(){
  54.     fastip();
  55.  
  56.     init();
  57.     backtrack(0,0);
  58.  
  59.     cin >> n;
  60.  
  61.     for(int i = 0; i < beautiful_number.size() ; i++){
  62.         string k = beautiful_number[i];
  63.         correct_number.push_back(stoll(k));
  64.     }
  65.  
  66.     sort(correct_number.begin(),correct_number.end());
  67.  
  68.     int pos = upper_bound(correct_number.begin(),correct_number.end(), n + 1) - correct_number.begin();
  69.     cout << correct_number[pos];
  70.  
  71.     return 0;
  72. }
Success #stdin #stdout 0.01s 5320KB
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https://ideone.com/iu48bB
language:
C++ (gcc 8.3)
created:
5 days ago
visibility:
public

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