Character Frequency Counter

Problem

Given a string s, return a dictionary where each key is a character from the string and each value is the number of times that character appears. Count all characters exactly as they appear, including uppercase and lowercase letters, digits, punctuation, special characters, and whitespace.

Constraints

• 0 <= len(s) <= 10^5
• s may contain letters, digits, punctuation, symbols, and whitespace
• Character comparison is case-sensitive