#include <stdio.h>
#include <stdlib.h>

// Linear search in an unsorted array.

void print_array(int a[], int n)
{
	int i;

	printf("\nIndex i:      ");
	for(i=0; i< n; i++)
		printf("%2d, ", i);

	printf("\nElement a[i]: ");
	for(i=0; i< n; i++)
		printf("%2d, ", a[i]);
			
	printf("\n\n");
}

#define N 12

int main()
{
	int a[N]= { 4, 7, 8, 10, 14, 21, 22, 36, 62, 77, 81, 91};
	int i;
	
	print_array(a, N);
	
	// Search for the target using Binary Search
	// We assume that the array is already sorted in increasing order

	int target = 22;
	//int target = 72; // Try this target next
	
	printf("\nSearching for target= %d ...\n", target);

	int idx=-1; // if the target is found its index is stored here
		
	// initial values for the three search varaibles
	int first=0;
	int last= N-1; 
	int mid= (first + last)/2;

	while(last >= first)
	{
		if( a[mid] == target)
		{
			idx=mid;  // Found it!
			break;    // exit the while loop 
		} 
		else if(a[mid] > target)
		{
			// don't search in a[mid] ... a[last]
			last = mid-1;
		}
		else
		{
			// don't search in a[first] ... a[mid]
			first = mid +1;
		}
		
		// recalculate mid for the next iteration	
		mid = (first + last)/2; // integer division!
		
	} // end of while loop
	

	if(idx == -1)
		printf("Target not found.\n\n");
	else
		printf("Target found at index: %d \n\n", idx);
	
	system("pause");
}