binary search com\ code example

Example 1: binary search in c++

#include<iostream> 
using namespace std; 
int binarySearch(int arr[], int p, int r, int num) { 
   if (p <= r) { 
      int mid = (p + r)/2; 
      if (arr[mid] == num)   
         return mid ; 
      if (arr[mid] > num)  
         return binarySearch(arr, p, mid-1, num);            
      if (arr[mid] < num)
         return binarySearch(arr, mid+1, r, num); 
   } 
   return -1; 
} 
int main(void) { 
   int arr[] = {1, 3, 7, 15, 18, 20, 25, 33, 36, 40}; 
   int n = sizeof(arr)/ sizeof(arr[0]); 
   int num = 33; 
   int index = binarySearch (arr, 0, n-1, num); 
   if(index == -1)
      cout<< num <<" is not present in the array";
   else
      cout<< num <<" is present at index "<< index <<" in the array"; 
   return 0; 
}

Example 2: binary search

import java.util.Scanner;

public class Binarysearch {

	public static void main(String[] args) {
		int[] x= {1,2,3,4,5,6,7,8,9,10,16,18,20,21};
		Scanner scan=new Scanner(System.in);
		System.out.println("enter the key:");
		int key=scan.nextInt();
		int flag=0;
		int low=0;
		int high=x.length-1;
		int mid=0;
		while(low<=high)
		{
			mid=(low+high)/2;
			if(key<x[mid])
			{
				high=mid-1;
			}
			else if(key>x[mid])
			{
				low=mid+1;
			}
			else if(key==x[mid])
			{
				flag++;
				System.out.println("found at index:"+mid);
				break;
			}
		}
		if(flag==0)
		{
			System.out.println("Not found");
		}
		

	}

}

Example 3: binary search

//it is using divide and conquer method
#include <iostream>

using namespace std;
void binarysearch(int arr[],int start,int end,int val)
{
    if(start<end)
    {
        int mid=(start+end)/2;
        if(arr[mid]==val)
        {
            cout<<"value found:"<<endl;
        }
        else if(arr[mid]<val)
        {
            binarysearch(arr,mid+1,end,val);
        }
        else if(arr[mid]>val)
        {
            binarysearch(arr,start,mid-1,val);
        }
    }
    else
    {
        cout<<"not present:"<<endl;
    }
}

int main()
{
    int n;
    cout<<"enter the size of the array:"<<endl;
    cin>>n;
    int arr[n];
    cout<<"enter the elements of the array:"<<endl;
    for(int i=0;i<n;i++)
    {
        cin>>arr[i];
    }
    cout<<"enter the value you want to search:"<<endl;
    int val;
    cin>>val;
    binarysearch(arr,0,n-1,val);

    return 0;
}

Example 4: binary search algorithm

#include <bits/stdc++.h>

using namespace std;

int binarySearch(int arr[], int l, int h, int key){
    if(l<=h){
        int mid = l + (h-l)/2;

        if(arr[mid] == key){
            return mid;
        }

        else if(arr[mid] > key){
            return binarySearch(arr, l, mid-1, key);
        }

        else if(arr[mid] < key){
            return binarySearch(arr,mid+1, h, key);
        }
    }       

    return -1;
}

int main(){
    int arr[] = {1,2,3,4,5,6,7,8,9,10};
    int n = sizeof(arr)/sizeof(arr[0]);
    int key = 7;

    int result = binarySearch(arr,0,n-1,key);

    (result==-1)
        ? cout << "Element is not found in the array" << endl
        : cout << "Element is found at index " << result;

    return 0;

}

Example 5: binary search

//Binary search can apply to sorted data only.
//Time complexity of binary search is O(log n ).
//It always divide the whole data in parts and compare  a search key to middle element only.


import java.util.*;
public class BinarySearch {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner sc = new Scanner(System.in);
		int[] a = {10,20,50,30,40};
		int key=sc.nextInt();
		
		Arrays.sort(a);					// An method in java.util.Arrays package to sort an array element.
		
		int first=0,end=a.length-1,mid=0,flag=0;

		while(first<=end)
		{
			mid=(first+end)/2;
			if(key<a[mid])				// Move to left part if key is smaller than middle element.
			{
				end = mid-1;
			}
			else if(key>a[mid])		   // Move to right part if key is greater than middle element.
			{
				first = mid+1;
			}
			else
			{
				flag=1;
				break;
			}
		}
		if(flag==1)
		{
			System.out.println("Success! found");
		}
		else
		{
			System.out.println("Error! This key (" + key + ") does not exist in the array");
		}
		
	}

}

Example 6: binary search

function binarySearchRicorsivo(array A, int p, int r, int v)
    if p > r
      return -1
     if v < A[p] or v > A[r]
       return -1
     q= (p+r)/2
     if A[q] == v
       return q
     else if A[q] > v
       return binarySearchRicorsivo(A,p,q-1,v)
     else