Thread: A Problem with recursion

I'm guessing he's required to use recursion.

Why do you check to see if Pivot-left or right-Pivot are not equal to one? Also, I'm not sure that last if statement will work the way you intend it, order of operations says to evaluate the && first and then the || second.

Heres a simple example of how this function probably doesn't work: Search for the number 2 in the simple array {0,2}. You'd call q_search(ray, 2, 0, 1). The pivot would be 0, the first if statement fails because ray[0] is less than 2, the second if statement fails because right-Pivot equals 1, the third if statement fails because ray[0] is not equal to 2 and the last if statement is true because right-Pivot equals 1 and (true || false && false)==true. It then returns -1 even though the number 2 is actually in the array.

The recursive version of the quick find is usually something like this:

Code:

int q_search(int ray[], int find, int left, int right)
{
   return -1 if left>right

   if left==right and ray[left] isn't the number you are looking for return -1, if it is return left

   pivot=(left+right)/2

   if ray[pivot] is the number you're looking for, return pivot

   if ray[pivot] is greater than the number, return q_search(ray, find, left, pivot-1)
   else return q_search(ray, find, pivot+1, right)

}