#P10571. Avoiding Powers of Two Substrings
Avoiding Powers of Two Substrings
Avoiding Powers of Two Substrings
You are given a string s
consisting of digits from 1 to 9. The number represented by s
is defined in the usual way as a decimal number:
\(\displaystyle Number(s)=\sum_{i=1}^{n}10^{n-i}\,s_i\)
You are allowed to perform several operations. In each operation, you can choose any position \(1\le p\le n\) and change the digit \(s_p\) to any digit from 1 to 9. Your goal is to modify s
so that there is no non-empty contiguous substring of s
whose numeric value is equal to \(2^k\) for some non-negative integer \(k\). Formally, there should be no substring s[l...r]
such that
\[
\sum_{i=l}^{r}10^{r-i}\,s_i = 2^k\quad (k\in \mathbb{N}).
\]
Compute the minimum number of operations required.
inputFormat
The input consists of a single line containing the string s
(digits 1-9 only).
outputFormat
Output a single integer, representing the minimum number of operations required.
sample
16
1