P10168 [DTCPC 2024] 0=1=0
Description
You are given a string $s$ that contains only $0$ and $1$.
Each time, you may choose an index $i\in [1,n)$, and flip $s_i$ and $s_{i+1}$ separately.
Flipping $1$ results in $0$, and flipping $0$ results in $1$.
You need to maximize the number of ordered pairs, i.e., maximize the number of pairs $(i,j)$ such that $i\lt j$ and $s_i\lt s_j$.
Output a solution.
Input Format
One line containing a string $S$ ($\lvert S\rvert\leq 2\times 10^5$).
Output Format
The first line outputs a number, representing the maximum number of ordered pairs.
The second line outputs a number $x$, representing the number of operations.
Then output one line with $x$ numbers. The $i$-th number $a_i$ means that in the $i$-th operation, you flip $s_{a_i}$ and $s_{a_i+1}$.
**You must ensure that the number of operations does not exceed $2\times 10^5$, but you do not need to minimize the number of operations.**
Explanation/Hint
Translated by ChatGPT 5