I think problem D should be easy.

I have been participating AtCoder Beginner Contest for about 1 year. I am a beginner, I have done 5 problems for only once. Anyway, I hope I can get five problems this time. Wishing everyone have fun and good luck!

PS: I am a Chinese student, if there are some fault in the words above, please forgive me!

I love coding!

Solved A $$$\sim$$$ F, wonder how to solve G

Wonder how E,F，could anyone give me a help？

Why did I get an RE+WA in D?Can anyone help me? my submission

Strange things happening with my code for problem D. It show wrong answer for sample test case but it is showing correct answer in my pc. Can anyone help me to find the problem in my code , please ~~~~~ Your code here...

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ll f = 0 ;
ll t = 0;
ll a ;

ll rer ( ll pos )
{
    if( 2*pos > a )
    {
        t += 1 ;
        f = 1 ;
        return a-pos;
    }

    if( 2*pos == a ) 
    {
        t += 1;
        f = 1 ;
        return pos;
    }

    t += 1;
    ll x =  rer(2*pos);

    if( x <= pos )
    {
        return x;
    }
    else {
        f ^= 1 ;
        return x - pos ;
    }

}

void solve()
{   

   ll n , q ;  
   string s; cin>>s;
   // cout << s << nl;
   cin>>q; 
   n = s.size() ;

   while( q-- )
   {
      cin>>a;
      f = 0 , t = 0;
      if( a <= n )
      {
        cout << s[a-1] <<" ";
        continue;
      }

      int x = rer(n);
      x--;
      char c = s[x];
      if( f ) 
      {
        if( (char)isupper(c) ) cout << (char)tolower(c) <<" ";
        else cout << (char) toupper(c) << " ";  
      }
      else cout << c << " ";
   }
   
   cout << nl;

}

I read the editorial of D problem. Can anyone explain why counting number of set bits in binary representation helps us determine if the character is flipped or not?

Can anyone please check my code for E — 1D Bucket Tool giving WA. I have used a set to keep a track of all the starting position of any particular colour, and tried to update the count on every new type 1 query.

Link: MY_SOLUTION