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# C: Bits

https\://open.kattis.com/problems/bits

* Firstly, we can keep successively (integer) dividing the number by $$10$$ to obtain the previous states of the calculator.
* Now, for each such number, we need to count the number of ones in the binary representation, and find the maximum value among those counts.
* This is now the classic problem of **converting a number to its binary representation**. 
  * There are builtin functions to do this! `bin(x)` in Python, `Integer.toBinaryString(x)` in Java, and `bitset<32>(x).to_string()` in C++ all give you the binary representation of the number.

{% hint style="info" %}
C++ is amazing: `__builtin_popcount(x)` directly gives you the number of ones in the binary representation of the integer `x`!
{% endhint %}