| **Note: This is the easier version of [Chapter 2](https://www.facebook.com/codingcompetitions/hacker-cup/2022/round-2/problems/A2). This version involves a string, but chapter 2 involves an array of integers that can change with updates.** | |
| A string is *perfectly balanced* if its length is even, and the first half of the string can be shuffled to make the string a palindrome. For example, "`abab`" and "`dood`" are perfectly balanced, but "`racecar`" and "`doodad`" are not. | |
| A string is *almost perfectly balanced* if you can delete exactly one character from it to make it perfectly balanced. Some examples are "`classical`", "`intelligent`", and "`www`". | |
| {{PHOTO_ID:1262846811180772|WIDTH:700}} | |
| You are given a larger template string \(S\), and \(Q\) substrings, the \(i\)th of which is \(S_{L_i..R_i}\). For how many of these \(Q\) queries is the substring almost perfectly balanced? | |
| # Constraints | |
| \(1 \le T \le 90\) | |
| \(1 \le |S| \le 10^6\) | |
| \(S_i \in\) {'`a`', ..., '`z`'} | |
| \(1 \le Q \le 10^6\) | |
| \(1 \le L_i \le R_i \le |S|\) | |
| The sum of \(|S|\) across all test cases is at most \(4{,}000{,}000\). | |
| The sum of \(Q\) across all test cases is at most \(4{,}000{,}000\). | |
| # Input Format | |
| Input begins with a single integer \(T\), the number of test cases. For each test case, there is first a line containing a single template string \(S\). Then, there is a line containing a single integer \(Q\). Then, \(Q\) lines follow, the \(i\)th of which contains two space-separated integers \(L_i\) and \(R_i\). | |
| # Output Format | |
| For the \(i\)th test case, output a single line containing `"Case #i: "`, followed by a single integer: the number of queries which are an almost perfectly balanced substring. | |
| # Sample Explanation | |
| In the first case, the template string is "`singingbanana`". | |
| For the first query, the substring is "`banan`". You can delete the `"b"` to get "`anan`" then reorder the first half of the string to get `"naan"`, which is a palindrome. Thus, "`banan`" is an almost perfectly balanced substring. | |
| For the second query, the substring is "`anana`". You can delete the second "`a`" to get "`anna`", which is a palindrome. Thus, "`anana`" is an almost perfectly balanced substring. | |
| For the third query, the substring is "`ban`". You cannot delete any character to get an almost perfectly balanced substring. | |
| For the fourth query, the substring is "`nan`". You can delete the "`a`" to get "`nn`", which is a palindrome. Thus, "`nan`" is an almost perfectly balanced substring. | |
| For "`singing`", you can create "`gniing`". | |
| In the second test case, the first, second, and third queries are almost perfectly balanced substrings, but the fourth is not. | |
| In the third test case, the first, second, third, and fourth queries are almost perfectly balanced substrings, but the fifth and sixth are not. | |