Count how many times each word appears and show the result in a dictionary.

To count word frequencies, split the input text into words, normalize them (e.g., lower‑case, strip punctuation), and iterate through the list, updating a dictionary where keys are words and values are counts. In Python, this can be done with a simple for‑loop or using collections.Counter. The algorithm runs in O(n) time, where n is the number of words, and uses O(k) additional space for k unique words. Example:

import re
from collections import Counter

def word_count(text):
    words = re.findall(r"\b\w+\b", text.lower())
    return Counter(words)

text = "Hello world! Hello again."
print(word_count(text))  # Counter({'hello': 2, 'world': 1, 'again': 1})

This approach handles large inputs efficiently and can be extended to ignore stop words or perform case‑insensitive matching as needed.