Write a Python function that reverses a string.
Implement an in-place quicksort in Python with a clear pivot strategy.
Given a list of intervals, write Python code to merge overlapping intervals.
Implement a Python LRU cache class with get and put methods.
Write a Rust function that counts frequencies of strings in a slice.
Implement a retry helper with exponential backoff and jitter in Python.
Write a Go function that checks whether all needles occur in a haystack slice.
Implement a TypeScript function groupBy(items, keyFn) returning Record<string, T[]>.
Write a concise explanation and implementation of binary search in Python.
Implement a Python function that finds the longest common subsequence of two strings.
