Rearrange positive and negative numbers with constant extra space in C++

We are given an integer type array containing both positive and negative numbers, let's say, arr[] of any given size. The task is to rearrange an array in such a manner that all the elements of an array are sorted using the inbuilt sort function of C++ STL as well as using recursive technique of coding and printing the result.

Let us see various input output scenarios for this −

Input − int arr[] = {4, 2, -1, -1, 6, -3, 0}

Output − Rearrangement of positive and negative numbers with constant extra space is: -3 -1 -1 0 6 2 4.

Explanation − we are given an integer array of size 7 containing both positive and negative elements. Now, we will rearrange the array in such a manner that all the elements of an array are sorted within the constant extra space and the final result will be -3 -1 -1 0 2 4 6.

Input − int arr[] = {-9, -10, 2, 3, 10, 5, 8, 4}

Output − Rearrangement of positive and negative numbers with constant extra space is: -9 -10 2 3 10 5 8 4

Explanation − we are given an integer array of size 8 containing both positive and negative elements. Now, we will rearrange the array in such a manner that all the elements of an array are sorted within the constant extra space and the final result will be -9 -10 2 3 10 5 8 4.

Approach used in the below program is as follows

Input an array of integer type elements and calculate the size of an array.
Print an array before performing the rearrangement action using the FOR loop.
Call to the function Rearrangement(arr, size) by passing array and size of an array as a parameter.
Inside the function Rearrangement(arr, size)
- Declare an integer type variable as i to 0 and j to size -1.
- Start while(true). Inside the while, start another loop while arr[i] less than 0 AND i less than size then increment the i by 1.
- Start WHILE arr[j] greater than 0 AND j greater than 0 then decrement the j by 1.
- Check IF i less than j then set temp to arr[i], arr[i] to arr[j] and arr[j] to temp.
- ELSE, break.
Print the result.

Example

#include<iostream>
using namespace std;
void Rearrangement(int arr[], int size){
   int i = 0;
   int j = size - 1;
   while(true){
      while(arr[i] < 0 && i < size){
         i++;
      }
      while(arr[j] > 0 && j >= 0){
         j--;
      }
      if (i < j){
         int temp = arr[i];
         arr[i] = arr[j];
         arr[j] = temp;
      }
      else{
         break;
      }
   }
}
int main(){
   int arr[] = {4, 2, -1, -1, 6, -3, 0};
   int size = sizeof(arr)/sizeof(arr[0]);
   //calling the function to rearrange the array
   Rearrangement(arr, size);
   //print the array after rearranging the values
   cout<<"Rearrangement of positive and negative numbers with constant extra space is: ";
   for(int i = 0; i < size; i++){
      cout<< arr[i] << " ";
   }
   return 0;
}

Output

If we run the above code it will generate the following Output

Rearrangement of positive and negative numbers with constant extra space is: -3 -1 -1 0 6 2 4

Sunidhi Bansal

Updated on 02-Nov-2021 06:54:58

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