Question

In details explain(the idea in pseudocode) and implement (in java) the following problem: Given a target value and a sorted array, assuming no duplicates in that array, if the target is found in the array, return its index. If not, return where it should be inserted(why it should be inserted there). Give a O(log n) time algorithm.

Example: {2,5,8,10}, target=5, returns 1. {2,5,8,10}, target=6, returns 2.

Answer 1

//Binarysearch.java
import java.util.Scanner;

public class BinarySearch {

    private static int binarySearch(int[] input, int low, int high, int key) {
        int mid;
        if(low<=high){
            mid = (low+high)/2;
            if(input[mid] == key){
                return mid;
            }
            else if(input[mid] < key){
                return binarySearch(input,mid+1,high,key);
            }
            else{
                return binarySearch(input,low,mid-1,key);
            }
        }
        return -1;
    }



    public static void main(String[] args) {
        int arr[] = {2,5,8,10};
        System.out.println(binarySearch(arr,0,arr.length-1,5));

        int arr2[] = {2,5,8,10};
        System.out.println(binarySearch(arr2,0,arr.length-1,6));
    }
}