Binary Search algorithm

Question

I'm using binary search to locate a record. My question is not about whether the data is present or not. I'll list my questions below.

1. if data are in following order

1 2 3 4 4 5 5 5 6 7 8 8 9 10 11

If now i want to search 5 where it is locate first. By using binary search algorithm I can get the 5 is present or not. in the above case i can get the 6th location of 5( totally 13 data) . But I need to get 5th location. How can i get this using binary search ? Once again in some cases i need to get last position of the given data. How can i get this binary search algorithm.

Is there any fastest method than binary search ? Not but hashing method ?

Answer 1

You could use a binary search again.

1. To get the lowest value of 5, start the search again but with its upper bounds 1 less than the current found value of 5.
2. To get the higest value of 5, start the search again but with its lower bounds 1 greater than the current found value of 5.

You must repeat the process above until you can no longer find the item, when you can no longer find the item, the last item found was the one you were looking for.

• Angelom: Made a change, if you are happy, mark the question as answered.