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  1. #include<bits/stdc++.h>
  2. using namespace std;
  3. long long n,k;
  4. string s;
  5. void backtrack(long long pos, long long val)
  6. {
  7.     if(pos==n) // đến số n
  8.     {
  9.         cout << s << "\n";
  10.         return;
  11.     }
  12.     for (long long i=!(n-pos>k-val); i<=(k-val>0); i++)
  13.     {
  14.  
  15.         s[2*pos]=char(i+'0');
  16.         s[2*pos+1]=' ';
  17.         if(i==0)
  18.         {
  19.             backtrack(pos+1,val);
  20.         }
  21.         else
  22.         {
  23.             backtrack(pos+1,val+1);
  24.         }
  25.  
  26.     }
  27. }
  28. int main()
  29. {
  30.     ios_base::sync_with_stdio(0);
  31.     cin.tie(0);
  32.     cin >> n >> k;
  33.     for (long long i=1; i<=2*n+1; i++)
  34.     {
  35.         s+=' ';
  36.     }
  37.     backtrack(0,0);
  38.     return 0;
  39. }
  40.  
Success #stdin #stdout 0s 5308KB
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https://ideone.com/rnAyHY
language:
C++14 (gcc 8.3)
created:
4 days ago
visibility:
public

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