Problem:
Score : 600 points

Problem Statement

You are given a string s consisting of A, B and C.

Snuke wants to perform the following operation on s as many times as possible:

Choose a contiguous substring of s that reads ABC and replace it with BCA.

Find the maximum possible number of operations.

Constraints

1 \leq |s| \leq 200000

Each character of s is A, B and C.

Input

Input is given from Standard Input in the following format:

s

Output

Find the maximum possible number of operations.

Sample Input 1

ABCABC

Sample Output 1

3

You can perform the operations three times as follows: ABCABC → BCAABC → BCABCA → BCBCAA. This is the maximum result.

Sample Input 2

C

Sample Output 2

0

Sample Input 3

ABCACCBABCBCAABCB

Sample Output 3

6

Solution in Java8 (OpenJDK 1.8.0) (judge verdict: Wrong Answer)


import java.util.Scanner;

public class Main {
    public static void main(final String[] args) {
        final Scanner scanner = new Scanner(System.in);
        final String s = scanner.next();

        long count = 0;
        long constraintA = 0;

        int i = 0;
        while (i < s.length()) {
            final char c = s.charAt(i);
            if (c == 'A') {
                long tmp = i;
                while (i < s.length() && s.charAt(i) == 'A') {
                    i++;
                }
                final long aCount = i - tmp + constraintA;

                tmp = i;
                while (i < s.length() - 1 && s.charAt(i) == 'B' && s.charAt(i + 1) == 'C') {
                    i += 2;
                }
                final long bcCount = (i - tmp) / 2;
                count += aCount * bcCount;
                constraintA += aCount;
            } else {
                constraintA = 0;
                i++;
            }
        }
        System.out.println(count);
    }
}