PracticeStrings

The Three-Class Character Tally

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Context

A finite string is viewed as a sequence of symbols. Each symbol belongs to exactly one of three classes: alphabetic characters, decimal digits, or all remaining characters. Determine how many symbols belong to each class.

Problem

Write a function that examines every character in symbols exactly once and counts the characters in three disjoint classes. An alphabetic character is an uppercase or lowercase English letter. A numeric character is one of the decimal digits 0 through 9. Every other character, including whitespace and punctuation, belongs to the remaining class. Return an integer list containing the totals in this order: alphabetic, numeric, other. Repeated characters are counted separately, and an empty string produces three zero totals.

Examples

Example 1

Input: symbols = "Hello, World! 123"

Output: [10, 3, 4]

Explanation: For "Hello, World! 123", the executed output is [10, 3, 4], in alphabetic, numeric, other order.

Example 2

Input: symbols = "A1-bB2!!"

Output: [3, 2, 3]

Explanation: For "A1-bB2!!", the executed output is [3, 2, 3], in alphabetic, numeric, other order.

Example 3

Input: symbols = " 007 #"

Output: [0, 3, 5]

Explanation: For " 007 #", the executed output is [0, 3, 5], in alphabetic, numeric, other order.

Constraints

0 <= len(symbols) <= 100000
symbols: alphanumeric
spaces and punctuation may also occur.
Types: symbols is str; result is int[]

Function signature

def count_character_classes(symbols: str) -> list[int]

symbols str: The string whose characters are classified and counted.
returns list[int]: Three integers in order: the number of alphabetic characters, numeric characters, and other characters.

Adapted from MBPP problem task_828 (CC BY 4.0). Rewritten, extended and verified by Iksha.

Code

Saved

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symbols =