A > B substring

AtCoder

IDabc441_e

Time2000ms

Memory256MB

Difficulty—

You are given a string $S$ of length $N$ consisting of three kinds of characters: `A`, `B`, and `C`. There are $\dfrac{N(N+1)}2$ non-empty contiguous substrings of $S$. Find how many of them contain more `A`s than `B`s. Note that two substrings are counted separately if they are taken from different positions in $S$, even if they are equal as strings. What is a substring?A **substring** of $S$ is a string obtained by deleting zero or more characters from the beginning and zero or more characters from the end of $S$. For example, `AB` is a substring of `ABC`, but `AC` is not a substring of `ABC`. ## Constraints * $1\le N\le5\times10 ^ 5$ * $S$ is a string of length $N$ consisting of `A`, `B`, and `C`. * $N$ is an integer. ## Input The input is given from Standard Input in the following format: $N$ $S$ [samples]

Samples

Input #1

10
ACBBCABCAB

Output #1

8

The following eight substrings satisfy the condition:

*   `A`: 1st to 1st character of $S$
*   `AC`: 1st to 2nd character of $S$
*   `CA`: 5th to 6th character of $S$
*   `CABCA`: 5th to 9th character of $S$
*   `A`: 6th to 6th character of $S$
*   `ABCA`: 6th to 9th character of $S$
*   `CA`: 8th to 9th character of $S$
*   `A`: 9th to 9th character of $S$

All other substrings do not satisfy the condition, so print `8`.
Note that `A` and `CA` can be taken from multiple positions, but they are counted separately if taken from different positions.

Input #2

4
CCBC

Output #2

0

There may be no substrings that satisfy the condition.

Input #3

36
CABACBBBBBAABABACCBCABCCABAABABBCBAC

Output #3

API Response (JSON)

{
  "problem": {
    "name": "A > B substring",
    "description": {
      "content": "You are given a string $S$ of length $N$ consisting of three kinds of characters: `A`, `B`, and `C`. There are $\\dfrac{N(N+1)}2$ non-empty contiguous substrings of $S$. Find how many of them contain m",
      "description_type": "Markdown"
    },
    "platform": "AtCoder",
    "limit": {
      "time_limit": 2000,
      "memory_limit": 262144
    },
    "difficulty": "None",
    "is_remote": true,
    "is_sync": true,
    "sync_url": null,
    "sign": "abc441_e"
  },
  "statements": [
    {
      "statement_type": "Markdown",
      "content": "You are given a string $S$ of length $N$ consisting of three kinds of characters: `A`, `B`, and `C`.\nThere are $\\dfrac{N(N+1)}2$ non-empty contiguous substrings of $S$. Find how many of them contain m...",
      "is_translate": false,
      "language": "English"
    }
  ]
}

Full JSON Raw Segments