Program 7 - Index Sequential Search

	#include <stdio.h>
	int index_sequential(int a[], int n, int key){
	int index[50], i, j = 0, k, gap = 3;
	for(i = 0; i < n; i += gap){
	index[j++] = i;
	}
	//Check if last index is last element index
	if(index[j-1] != n - 1){
	index[j++] = n - 1;
	}
	for(i = 0; i < j - 1; i++){
	if(key >= a[index[i]] && key <= a[index[i+1]]){
	for(k = index[i]; k <= index[i + 1]; k++){
	if(key == a[k]){
	return k;
	}
	}
	}
	}
	return -1;
	}
	int main(){
	int a[] = {1,2,3,4,5};
	int n = sizeof(a) / sizeof(a[0]);
	int element;
	printf("Enter element to search: ");
	scanf("%d", &element);
	int pos = index_sequential(a, n, element);
	if(pos != -1){
	printf("Element found at position: %d\n", pos + 1);
	} else {
	printf("Element not found\n");
	}
	return 0;
	}