C Exercises: Rearrange positive and negative numbers alternatively in a given array

C Array: Exercise-93 with Solution

Write a program in C to rearrange positive and negative numbers alternatively in a given array.

N.B.: If positive numbers are more they appear at the end and for also negative numbers, they too appear in the end of the array.

Sample Solution:

C Code:

#include <stdio.h>
 
void changeNumber (int *arr1, int i, int j) 
{
    int temp = arr1[i];
    arr1[i] = arr1[j];
    arr1[j] = temp;
}

void splitPosNeg(int *arr1, int size)
{
    int temp, left = 0, right = size-1;
    while(right > left)
	{
     while(arr1[left] < 0)
         left++;
     while(arr1[right] > 0)
         right--;
     if(left < right)
	 {
            changeNumber(arr1, left, right);
        }
    }
}
 
void rearrangeNumbers(int *arr1, int size) 
{
    int i, j;
    splitPosNeg(arr1, size);
    for(i = 0; arr1[i] < 0; i++);
    for(j = 1; (j < i) && (arr1[j] < 0); j += 2)
	{
        changeNumber(arr1, i, j);
        i++;
    }
    return;
}
 
int main()
{
    int i, arr1[] = {-4, 8, -5, -6, 5, -9, 7, 1, -21, -11, 19}; 
	  int arr_size = sizeof(arr1)/sizeof(arr1[0]);	  
   //------------- print original array ------------------	
	printf("The given array is:  \n");
	for(i = 0; i < arr_size; i++)
		{
			printf("%d  ", arr1[i]);
		}
	printf("\n");
//----------------------------------------------------------- 
	printf("The rearranged array is:  \n");
    rearrangeNumbers(arr1, 10);
    for(i = 0; i < 11; i++){
     printf("%d ", arr1[i]);
    }
    return 0;
}

Sample Output:

The given array is:  
-4  8  -5  -6  5  -9  7  1  -21  -11  19  
The rearranged array is:  
-4 7 -5 1 -21 5 -11 8 -9 19 -6

Flowchart:

C Programming Code Editor:

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