insertion Sort Algorithm
Insertion sort is a simple sorting algorithm that builds the final sorted array (or list) one item at a time.
However, insertion sort provides several advantages:
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
Stable; i.e., makes not change the relative order of components with equal keys
/* In insertion sort, we divide the initial unsorted array into two parts;
* sorted part and unsorted part. Initially the sorted part just has one
* element (Array of only 1 element is a sorted array). We then pick up
* element one by one from unsorted part; insert into the sorted part at
* the correct position and expand sorted part one element at a time.
*/
function insertionSort (unsortedList) {
var len = unsortedList.length
for (var i = 1; i < len; i++) {
var tmp = unsortedList[i] // Copy of the current element.
/* Check through the sorted part and compare with the number in tmp. If large, shift the number */
for (var j = i - 1; j >= 0 && (unsortedList[j] > tmp); j--) {
// Shift the number
unsortedList[j + 1] = unsortedList[j]
}
// Insert the copied number at the correct position
// in sorted part.
unsortedList[j + 1] = tmp
}
}
var arr = [5, 3, 1, 2, 4, 8, 3, 8]
insertionSort(arr)
console.log(arr)
