Answers for "binary search algorithm"

binary search program c++

#include <iostream>
using namespace std;

// This program performs a binary search through an array, must be sorted to work
int binarySearch(int array[], int size, int value) 
{   
    int first = 0,         // First array element       
    last = size - 1,       // Last array element       
    middle,                // Mid point of search       
    position = -1;         // Position of search value   
    bool found = false;        // Flag   
    while (!found && first <= last) 
    {      
        middle = (first + last) / 2;     // Calculate mid point      
        if (array[middle] == value)      // If value is found at mid      
    	{         
                found = true;         
                position = middle;      
        }      
        else if (array[middle] > value)  // If value is in lower half         
            last = middle - 1;      
        else         
            first = middle + 1;          // If value is in upper half   
    }   
    return position;
}
int main ()
{
    const int size = 5; // size initialization
    int array[size] = {1, 2, 3, 4, 5}; // declare array of size 10
    int value; // declare value to be searched for
    int result; // declare variable that will be returned after binary search

    cout << "What value would you like to search for? "; // prompt user to enter value
    cin >> value;
    result = binarySearch(array, size, value);

    if (result == -1) // if value isn't found display this message
        cout << "Not found\n";
    else  // If value is found, displays message
        cout << "Your value is in the array.\n"; 
  
    return 0;
}

binary search java

// Java implementation of iterative Binary Search 
class BinarySearch { 
	// Returns index of x if it is present in arr[], 
	// else return -1 
	int binarySearch(int arr[], int x) 
	{ 
		int l = 0, r = arr.length - 1; 
		while (l <= r) { 
			int m = l + (r - l) / 2; 

			// Check if x is present at mid 
			if (arr[m] == x) 
				return m; 

			// If x greater, ignore left half 
			if (arr[m] < x) 
				l = m + 1; 

			// If x is smaller, ignore right half 
			else
				r = m - 1; 
		} 

		// if we reach here, then element was 
		// not present 
		return -1; 
	} 

	// Driver method to test above 
	public static void main(String args[]) 
	{ 
		BinarySearch ob = new BinarySearch(); 
		int arr[] = { 2, 3, 4, 10, 40 }; 
		int n = arr.length; 
		int x = 10; 
		int result = ob.binarySearch(arr, x); 
		if (result == -1) 
			System.out.println("Element not present"); 
		else
			System.out.println("Element found at "
							+ "index " + result); 
	} 
}

binary search function 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;
}

binary search

#binary search python
def binaryy(ar, ele):
    low = 0 
    high = len(ar)-1
    if ele not in ar:
        return "Not Found"
    while low <= high:
        mid = (low + high) // 2
        if ar[mid] < ele:
            low = mid + 1
        elif ar[mid] > ele:
            high = mid - 1
        else:
            return mid


ar = [10, 20, 30, 40, 50]
ele = 55
print(binaryy(ar, ele))

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");
		}
		

	}

}

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;

}