Orig Description
Score : 600 points
Problem StatementYou 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.
InputInput is given from Standard Input in the following format:
s
OutputFind the maximum possible number of operations.
Sample Input 1ABCABC
Sample Output 13
You can perform the operations three times as follows: ABCABC → BCAABC → BCABCA → BCBCAA. This is the maximum result.
Sample Input 2C
Sample Output 20
Sample Input 3ABCACCBABCBCAABCB
Sample Output 36
Extracted Specification
Canonicalized Input Description:
A string \( s \) consisting only of the characters 'A', 'B', and 'C', with length between 1 and 200000.
### Example Input:
```
ABCABC
```
### Function Signature:
Write a function f(s) that takes in the input.
```python
def f(s: str):
'''
s: a string
'''
```
Test Case Generator
Sure, I can help you write a test case generator for the given problem. The generator will create random strings of varying lengths containing the characters 'A', 'B', and 'C'. Here's the code:
```python
import random
def tcgen():
# Generate a random length for the string s
length = random.randint(1, 200000)
# Generate a random string of the given length consisting of 'A', 'B', and 'C'
s = ''.join(random.choice('ABC') for _ in range(length))
return s
# Example usage:
for _ in range(5): # Generate 5 test cases
print(tcgen())
```
### Explanation
1. **Length of String**: We generate a random integer between 1 and 200,000 for the length of the string, ensuring it meets the problem constraints.
2. **Generate String**: We then generate a string of the specified length composed of random characters chosen from the set {'A', 'B', 'C'}.
3. **Output**: The function returns the generated string.
This will generate test cases of varying lengths and compositions, ensuring comprehensive coverage for the problem.
### Example Output
Here's an example of what the output might look like when you run the `tcgen()` function:
```
BCABCA
A
CABCBACBACBBAC
...
```
Each string will be a random sequence of 'A', 'B', and 'C', suitable for testing the competitive programming problem's solution.