Insertion Sort Algorithm
Insertion sort is a simple sorting algorithm that builds the final sorted array (or list) one item at a time. It is much less efficient on large lists than more advanced algorithms such as quicksort, heapsort, or merge sort.
However, insertion sort provides several advantages:
1. Simple implementation: Jon Bentley shows a three-line c version, and a five-line optimized version
Efficient for (quite) small data sets, much like other quadratic sorting algorithmsAdaptive, i.e., efficient for data sets that are already substantially sorted: the time complexity is O(kn) when each component in the input is no more than K places away from its sorted position
2. Stable; i.e., makes not change the relative order of components with equal keys
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package com.algorithmexamples.sorts
/**
* Insertion sort iterates, consuming one input element each repetition, and growing a sorted output list.
* Each iteration, insertion sort removes one element from the input data, finds the location it belongs within
* the sorted list, and inserts it there. It repeats until no input elements remain.
*/
@ComparisonSort
@StableSort
class InsertionSort: AbstractSortStrategy() {
override fun <T : Comparable<T>> perform(arr: Array<T>) {
for (i in 1 until arr.size) {
for (j in i downTo 1) {
if (arr[j - 1] < arr[j]) break
arr.exch(j, j - 1)
}
}
}
}
