Shell Sort using arrays

#include <stdio.h>
#include <stdlib.h>
void swap(int *a, int *b){
    if(*a != *b){
        int t = *a; *a = *b; *b = t;
    }
}
void shellSort(int a[], int n){
    int i, j, k;
       for(i = n/2; i > 0; i = i/2)
            for(j = i; j < n; j++)
                for(k = j - i; k >= 0; k = k - i)
                    if(a[k+i] < a[k]) swap(&a[k+i], &a[k]);
                    else break;
}
int main(){
    int *a, i, n;
    printf("Enter the number of elements : ");
    scanf("%d", &n);
    a = (int *) malloc(sizeof(int) *n);
    for(i = 0; i < n; i++) scanf("%d", &a[i]);
    shellSort(a, n);
    printf("The sorted list is:-\n");
    for(i=0; i<n; i++) printf("%d\t", a[i]);
}