Merge sort with recursion

PHOTO EMBED

Sat Jan 28 2023 13:56:05 GMT+0000 (Coordinated Universal Time)

Saved by @Ranjan_kumar #c++ 

#include <bits/stdc++.h>
using namespace std;

void merge(int *arr, int s, int e)
{
   int mid = (s+e)/2;
   int len1=mid-s+1;
   int len2=e-mid;
   
   int *first = new int[len1];
   int *second=new int[len2];
   
   //copy value
   int mainArrayIndex = s;
   for(int i=0;i<len1;i++)
   {
      first[i]=arr[mainArrayIndex++];
   }
   mainArrayIndex=mid+1;
   for(int i=0;i<len2;i++)
   {
      second[i]=arr[mainArrayIndex++];
   }
   
   //merge 2 sorted arrays
   int index1=0;
   int index2=0;
   mainArrayIndex=s;
   
   while(index1<len1&&index2<len2)
   {
      if(first[index1]<second[index2])
      {
         arr[mainArrayIndex++]=first[index1++];
      }
      else 
      {
         arr[mainArrayIndex++]=second[index2++];
      }
   }
   while(index1<len1)
   {
      arr[mainArrayIndex++]=first[index1++];
   }
   while(index2<len2)
   {
      arr[mainArrayIndex++]=second[index2++];
   }
   delete []first;
   delete []second;
  
}
void mergesort(int *arr,int s,int e)
{
   //base case
   if(s>=e)
   {
      return;
   }
   
   int mid=(s+e)/2;
   //left part sort karna h
   mergesort(arr, s, mid);
   //right part sort karna right
   mergesort(arr, mid+1, e);
   
   //merge
   merge(arr,s,e);
   
}
int main() {
   
	int a[5]={5,6,1,4,3};
   int n=5;
   mergesort(a,0,n-1);
	for(int i=0;i<5;i++)
	{
	   cout<<a[i]<<" ";
	}
	return 0;
}
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