Question

How to rearrange array and set even indexed values to be smaller than odd indexed values in C

Answer 1

#include <stdio.h>

void swap(long* x, long* y) {
    long tmp = *x;
    *x = *y;
    *y = tmp;
}

void RearrangeOddEven(int* arr, int size) {
    for (int i = 0; i < size - 1; i++) {
        if (i % 2 == 0 && arr[i] > arr[i + 1])
            swap(&arr[i], &arr[i + 1]);
        if (i % 2 != 0 && arr[i] < arr[i + 1])
            swap(&arr[i], &arr[i + 1]);
    }
}

void PrintArray(int arr[], int size) {
    for (int i = 0; i < size; i++)
        printf("%2d", arr[i]);
}

int main()
{
    int arr[] = { 1, 2, 3, 5, 8, 6, 7, 4 };

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

    RearrangeOddEven(arr, size);

    PrintArray(arr, size);

    return 0;
}




/*
run:

 1 3 2 8 5 7 4 6

*/

 

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