Learn: Merge Sort - The Big Idea (Divide and Merge)

Welcome!You've already studied sorting algorithms like Bubble Sort and Insertion Sort. Now, let's build on that by exploring Merge Sort. This algorithm uses a clever 'divide and merge' approach to sort data efficiently.

What is Merge Sort?Merge Sort is a sorting algorithm that divides a list into smaller parts, sorts each part, and then merges them back together in the correct order. It's faster than Bubble Sort and Insertion Sort for large lists because it reduces the number of comparisons.

Divide and ConquerThe key idea behind Merge Sort is Divide and Conquer. First, the list is split into smaller sublists until each sublist contains only one item. Then, these sublists are merged back together in sorted order. This process ensures efficiency.

How Does Merge Sort Work?Merge Sort works in two main phases: Divide and Merge. During the divide phase, the list is repeatedly split in half until each sublist contains just one item. During the merge phase, the sublists are combined back together in sorted order.

Why Is Merge Sort Efficient?Merge Sort is efficient because it reduces the problem size at each step. By dividing the list and sorting smaller parts, it ensures fewer comparisons overall. This makes it faster than other sorting algorithms like Bubble Sort for large datasets.

Steps of Merge Sort1. Divide the list into two halves repeatedly until each sublist contains only one element.2. Compare the elements in the sublists and merge them into a larger sorted list.3. Repeat the merging process until all sublists are merged into one sorted list.

Review Time!Well done! You've learned about Merge Sort and how it uses 'divide and conquer' to sort lists efficiently. Let's test your understanding with some questions.

Why Use Merge Sort?Merge Sort is especially useful when you need to sort large datasets efficiently. It has a consistent time complexity of O(n log n), making it faster than algorithms like Bubble Sort and Insertion Sort for sorting large lists.