Segregate Even and Odd numbers

Segregate Even and Odd numbers

Given an array A[], write a function that segregates even and odd numbers. The functions should put all even numbers first, and then odd numbers.

// C program to segregate even and odd elements of array

#include<stdio.h>

/* Function to swap *a and *b */

void swap(int *a, int *b);

void segregateEvenOdd(int arr[], int size)

{

    /* Initialize left and right indexes */

    int left = 0, right = size-1;

    while (left < right)

    {

        /* Increment left index while we see 0 at left */

        while (arr[left]%2 == 0 && left < right)

            left++;

        /* Decrement right index while we see 1 at right */

        while (arr[right]%2 == 1 && left < right)

            right--;

        if (left < right)

        {

            /* Swap arr[left] and arr[right]*/

            swap(&arr[left], &arr[right]);

            left++;

            right--;

        }

    }

}

/* UTILITY FUNCTIONS */

void swap(int *a, int *b)

{

    int temp = *a;

    *a = *b;

    *b = temp;

}

/* driver program to test */

int main()

{

    int arr[] = {12, 34, 45, 9, 8, 90, 3};

    int arr_size = sizeof(arr)/sizeof(arr[0]);

    int i = 0;

    segregateEvenOdd(arr, arr_size);

    printf("Array after segregation ");

    for (i = 0; i < arr_size; i++)

        printf("%d ", arr[i]);

    return 0;

}

Output:

Array after segregation 12 34 90 8 9 45 3

Example:

Input  = {12, 34, 45, 9, 8, 90, 3}

Output = {12, 34, 8, 90, 45, 9, 3}