QuickSort: O(n log n) avg-case, O(n²) worst-case. Divide-and-conquer algo with good locality of reference & in-place sorting. However, unstable & poor on already sorted data.

Merge Sort: O(n log n) time complexity & O(n) space complexity. Divide array into smaller subarrays, sort recursively, then merge back together. Optimizations include hybrid with Insertion Sort & in-place merging.

Selection Sort has a time complexity of O(n²), space complexity of O(1). Inefficient for large datasets, but simple to understand and implement.

Implementing Stripe payment system in Flutter: Set up Stripe account & API keys, install `stripe` package, create payment service class, handle payment flow, integrate with app using Riverpod's state management for error handling & logging.