Binary search algorithm

CaCao · #1 31-Mar-2007, 04:44

Hey guys I need a big help.

I have an algorithm about binary search and I need this algorithm's program.
couldnt do it

If anyone can do it for me I will be so happy.

here is the algorithm:
__________________________________________________ ____________
1.0 Let the bottom be the initial array elements.

2.0 Let the top be the last array elements.

3.0 Let found false.

4.0 Repeat as long as bottom is not greater than top and target has not been found.

4.1 Let the middle be subscript of the element half way between bottom
and top.

4.2 If the element middle is target

4.2.1 Set found to true and index ot middle.

4.3 Let top be the middle-1

__________________________________________________ _________

mathematician · #2 31-Mar-2007, 05:45

If you have reproduced it correctly, somebody has given you a flaky algorithm. That's not how you do a binary chop.

davekw7x · #3 31-Mar-2007, 15:08

Quote:

Originally Posted by mathematician

If you have reproduced it correctly, somebody has given you a flaky algorithm. That's not how you do a binary chop.

Indeed.

Problem statement for an array of integers:

Code:

Given a array of ints, array[], sorted in ascending order,
and int variables "target", "bottom" and "top".

"bottom" and "top" are the values of the indices of the
first and last elements of the array to be searched.

We are looking for the index of an element whose value
is equal to "target".

Binary search algorithm to be implemented in C:

Code:


Declare an integer variable "probe".
Declare an integer variable "found".

Set found = 0.

While (bottom is not greater than top) and (found is equal to 0)
Begin Loop
    
    Set probe = (bottom + top) / 2.
   
    If array[probe] is equal to the target value then
         Set found = 1.

    Else If array[probe] is greater than the target then
         Set top = probe-1.

    Else
         Set bottom = probe+1.

    End If

End Loop

Upon leaving the loop, if "found" == 1, then "probe" is the
index of an array element that is equal to the target value.

Regards,

Dave

CaCao · #4 01-Apr-2007, 04:42

Quote:

If you have reproduced it correctly, somebody has given you a flaky algorithm. That's not how you do a binary chop.

The only information i have is that. Thats why I couldnt do anything.

Thanks a lot Dave

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