Algorithms

Searching Algorithms :

		
Linear search (Time complexity): O(n)
		
#include<iostream>
using namespace std;

void linear_search(int *arr,int n,int element)
{
    int counter = 0,i;
    for( i = 0 ; i < n ; i++)
    {
        if(element == arr[i])
        {
            cout<<"Element is found at "<<counter+1<<"th position"<<endl;
            break;
        }
        counter++;
    }
    if(i == n)
    {
        cout<<"Element not found"<<endl;
    }
}
int main()
{
    int n;
    cout<<"Enter the size of array : ";
    cin>>n;
    int arr[n];
    cout<<"\nEnter the element of array : "<<endl;
    for(int i = 0 ; i < n ; i++)
    {
        cin>>arr[i];
    }
    int element;
    cout<<"\nEnter the element you want to find : ";
    cin>>element;
    linear_search(arr,n,element);
    return 0;
}
	

		
Binary search (Time complexity): O(log n)
		
#include<iostream>
#include<algorithm>
using namespace std;

int Binary_search(int *arr,int left,int right,int element)
{
   int middle;
   if(right >= left)
   {
       middle = (left + right)/2;
       if(arr[middle] == element)
       {
           return middle+1;
       }
       else if(arr[middle] < element)
       {
           return Binary_search(arr,middle+1,right,element);
       }
       else
       {
           return Binary_search(arr,left,middle-1,element);
       }
   }
   return -1;
}
int main()
{
    int n;
    cout<<"Enter the size of array : ";
    cin>>n;
    int arr[n];
    cout<<"\nEnter the element of array : ";
    for(int i = 0 ; i < n ; i++)
    {
        cin>>arr[i];
    }
    sort(arr,arr+n);
    int element;
    cout<<"\nEnter the element you want to find : ";
    cin>>element;
    cout<<"\nSorted array : ";
    for(int i = 0 ; i < n ; i++)
    {
        cout<<arr[i]<<" ";
    }
    int position = -1;
    position = Binary_search(arr,0,n,element);
    cout<<endl;
    if(position != -1)
    {
        cout<<"\nIn sorted array Element found at "<<position<<"th place"<<endl;
    }
    else
    {
        cout<<"\nElement not found"<<endl;
    }
    return 0;
}

	

Sorting Algorithms :

    
Bubble sort (Time complexity): O(n2)
    
#include <iostream>
using namespace std;

void swap_arr(int *no1, int *no2)
{
  *no1 =  *no1 + *no2;
  *no2 =  *no1 - *no2;
  *no1 =  *no1 - *no2;
}

void bubbleSort(int *arr, int n)
{
  int i, j;
  for (i = 0; i < n-1; i++)
    {
        for (j = 0; j < n-i-1; j++)
        {
            if (arr[j] > arr[j+1])
            {
                swap_arr(&arr[j], &arr[j+1]);
            }
        }
    }
}

void printArray(int *arr, int n)
{
  int i;
  for (i = 0; i < n; i++)
    {
    cout << arr[i] << " ";
    }
  cout << endl;
}

int main()
{
    int n;
    cout<<"Enter the size of the array : ";
    cin>>n;

    int arr[n];
    cout<<"\nEnter the elements of the array : ";
    for(int i = 0 ;i < n ;i++)
    {
        cin>>arr[i];
    }

    cout<<"\nBefore sort : ";
    printArray(arr, n);

    bubbleSort(arr, n);
    cout<<"\nAfter sort: ";
    printArray(arr, n);
    return 0;
}
  

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