Algorithm Insertion Sort Searching and Sorting

Binary Insertion Sort

Binary insertion sort
Binary Insertion Sort - Searching and Sorting - We can use binary search to reduce the number of comparisons in normal insertion sort. Binary Insertion Sort find use binary search to find the proper location to insert the selected item at each iteration.

Binary Search

We can use binary search to reduce the number of comparisons in normal insertion sort. Binary Insertion Sort find use binary search to find the proper location to insert the selected item at each iteration.
In normal insertion, sort it takes O(i) (at ith iteration) in worst case. we can reduce it to O(logi) by using binary search.

diagram for binary insertion sort

Implementation of Binary Insertion Sort in C

C
// C program for implementation of binary insertion sort
#include <stdio.h>
 
// A binary search based function to find the position
// where item should be inserted in a[low..high]
int binarySearch(int a[], int item, int low, int high)
{
    if (high <= low)
        return (item > a[low])?  (low + 1): low;
 
    int mid = (low + high)/2;
 
    if(item == a[mid])
        return mid+1;
 
    if(item > a[mid])
        return binarySearch(a, item, mid+1, high);
    return binarySearch(a, item, low, mid-1);
}
 
// Function to sort an array a[] of size 'n'
void insertionSort(int a[], int n)
{
    int i, loc, j, k, selected;
 
    for (i = 1; i < n; ++i)
    {
        j = i - 1;
        selected = a[i];
 
        // find location where selected sould be inseretd
        loc = binarySearch(a, selected, 0, j);
 
        // Move all elements after location to create space
        while (j >= loc)
        {
            a[j+1] = a[j];
            j--;
        }
        a[j+1] = selected;
    }
}
 
// Driver program to test above function
int main()
{
    int a[] = {37, 23, 0, 17, 12, 72, 31,
              46, 100, 88, 54};
    int n = sizeof(a)/sizeof(a[0]), i;
 
    insertionSort(a, n);
 
    printf("Sorted array: \n");
    for (i = 0; i < n; i++)
        printf("%d ",a[i]);
 
    return 0;
}

Output:

Sorted array:
0 12 17 23 31 37 46 54 72 88 100

Time Complexity: The algorithm as a whole still has a running worst case running time of O(n2) because of the series of swaps required for each insertion.

Implementation of Binary Insertion Sort in JAVA

In this implementation, I have used library functions for binary search and shifting array to one location right

package com.codingeek.algorithms.sorting;
 
import java.util.Arrays;
 
class BinaryInsertionSort{
 
    public static void main(String[] args) {
        final int[] input = { 4, 10, 3, 1, 9, 15 };
        System.out.println("Before Sorting - " + Arrays.toString(input));
        new BinaryInsertionSort().sort(input);
        System.out.println("After Sorting - " + Arrays.toString(input));
    }
     
    public void sort(int array[]) {
        for (int i = 1; i < array.length; i++) {
               int x = array[i];
                
               // Find location to insert using binary search
               int j = Math.abs(Arrays.binarySearch(array, 0, i, x) + 1);
                
               //Shifting array to one location right
               System.arraycopy(array, j, array, j+1, i-j);
                
               //Placing element at its correct location
               array[j] = x;
        }
}
Output:-
Before Sorting - [4, 10, 3, 1, 9, 15]
After Sorting - [1, 3, 4, 9, 10, 15]

 

About the author

Venkatesan Prabu

Wikitechy Founder, Author, International Speaker, and Job Consultant. My role as the CEO of Wikitechy, I help businesses build their next generation digital platforms and help with their product innovation and growth strategy. I'm a frequent speaker at tech conferences and events.

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