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What is Insertion Sort?
Insertion sort is a simple sorting algorithm that works by repeatedly taking an element from an unsorted list and inserting it into its correct position within a sorted portion of the list. It is an efficient and intuitive way to sort small to medium-sized data sets, especially when the elements are already partially sorted.
Explanation of the Basic Insertion Algorithm
The basic insertion sort algorithm follows the following steps:
1. We start by considering the second element in the list and assume it to be the first element of the sorted section. This is because a single element is always considered sorted in itself.
2. We compare the second element with the first element. If it is smaller, we swap them, which ensures that the first two elements are now in sorted order.
3. Now, we consider the third element, compare it with the second element, and continue swapping until it is in its correct position within the first three elements.
4. We repeat this process for each subsequent element in the unsorted section of the list:
– Compare the element with the elements in the sorted section, iterating from right to left, until we find its correct position.
– Shift the elements greater than the current element one position to the right to make room for the current element.
– Insert the current element into its correct position in the sorted section.
5. Repeat steps 4 until the entire list is sorted.
This process of inserting each unsorted element into its correct position within the sorted section is why it is called “insertion sort”. The algorithm continues in this manner until the entire list is sorted, gradually building up the sorted section from left to right.
Insertion sort is an in-place algorithm and its time complexity is O(n^2), where n is the number of elements in the list. However, it performs well for smaller data sets or partially sorted data due to its simplicity and efficient nature.
Note: Insertion sort is not recommended for sorting large data sets with hundreds of thousands of elements as it is relatively slower compared to more advanced sorting algorithms like merge sort or quicksort. It is most effective when the input size is small or when the data set is partially sorted.
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