Longest balanced binary substring
In a string of 0s and 1s, find the longest substring with the same number of 0s and 1s. Print its length (0 if there is none).
Reported in: Capgemini (2026 batch) (memory-based)
Input
One line: the binary string.
Output
The length.
Constraints
1 ≤ length ≤ 10^5.
Example 1
Input:
1101000
Output:
6Example 2
Input:
111
Output:
0Hint: Treat 0 as −1 and 1 as +1; equal prefix sums mark a balanced stretch. Store the first index of each prefix sum.