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Rearrange positive and negative numbers using inbuilt sort function 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 using inbuilt sort function is: -3 -1 -1 0 2 4 6.
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 i.e. all the negative elements appear before all the positive elements 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 using inbuilt sort function is: -10 -9 2 3 4 5 8 10.
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 i.e. all the negative elements appear before all the positive elements and the final result will be -10 -9 2 3 4 5 8 10.
Approach used in the below program is as follows
Using sort()
Input an array of integer type elements and calculate the size of an array.
Pass the data to the function Rearrangement(int arr[], int size)
Inside the function, Rearrangement(int arr[], int size)
Call the sort function of C++ STL by passing array and size of an array as a parameter to the function and it will return the sorted array.
Print the result.
Using Recursion
Input an array of integer type elements and calculate the size of an array.
Declare a temporary variable, let's say, temp.
Start loop FOR from i to till i less than size of an array. Inside the loop, check if arr[i] less than 0 then increment the temp by 1.
Call the Rearrangement(arr, 0, (size - 1)) by passing array, 0, and size -1 as a parameter to the function.
Call the rotate function by passing array, temp and size - 1 to the function.
Inside the function Rearrangement(int arr[], int first, int last)
Check IF first equals last then return.
Make a recursive call to the function Rearrangement() and pass array, first + 1 and last element as a parameter.
Check IF arr[first] greater than 0 then make a call to the function as Rotate(arr, (first + 1), last) and Rotate(arr, first, last)
Inside the function Rotate(int arr[], int first, int last)
Start while first less than last. Inside the while, declare the integer variable as temp and set it with arr[first] then set arr[first] to arr[last] and arr[last] to temp. Increment the first by 1 and decrement the last by 1.
Print the result.
1. Using the sort() function
Example
#include <bits/stdc++.h>
using namespace std;
//using the sort() function
void Rearrangement(int arr[], int size){
sort(arr, arr + size);
}
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 using inbuilt sort function 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 using inbuilt sort function is: -3 -1 -1 0 2 4 6
2. Recursive call to a function
Example
#include <bits/stdc++.h>
using namespace std;
void Rotate(int arr[], int first, int last){
while(first < last){
int temp = arr[first];
arr[first] = arr[last];
arr[last] = temp;
first++;
last--;
}
}
void Rearrangement(int arr[], int first, int last){
if(first == last){
return;
}
Rearrangement(arr, (first + 1), last);
if(arr[first] >= 0){
Rotate(arr, (first + 1), last);
Rotate(arr, first, last);
}
}
int main(){
int arr[] = {4, 2, -1, -1, 6, -3, 0};
int size = sizeof(arr)/sizeof(arr[0]);
int temp = 0;
for(int i = 0; i < size; i++){
if(arr[i] < 0){
temp++;
}
}
//calling the function to rearrange the array
Rearrangement(arr, 0, (size - 1));
Rotate(arr, temp, (size - 1));
//print the array after rearranging the values
cout<<"Rearrangement of positive and negative numbers using Recursion 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 using Recursion is: -1 -1 -3 4 2 6 0
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