Searching Algorithms That I Often Use

As a Computer Science student I have learn a lot of algorithm that not only usable in programming buat also in my daily life. For example, I save alot of time when using binary search for searching in ordered objects.

1. Hash Map

Hash Map using integer of hash function result of item's key to map object into bucket array. The object is mapped using modulo of hash value and bucket size as index in the bucket array. And if there is collision the item is added using linked list in the collided index. The item search is doing by calculate hash value of search key and using modulo to find index in the bucket array. And if index in bucket is occupied then continue to compare item's key with search key, if not equal then continue with items in the linked list until the key is equal, if all items is not equal then item is not found.

Using Hash Map is very fast for alot of items and is frequently searched but when new item is added and the bucket need to grow it need to rehash the entire bucket into new bucket.

2. Hash Marking

Hash marking using integer of hash function result of item's key to mark list items. Because comparing an integer only need 1 cpu clock and comparing text need 1 cpu clock per character we can skip comparing entire key by first comparing only hash values and only if it is equal then we continue to compare the key.

This method is very effective if item's key is a string or large complex type such as struct. For very alot of items and is frequently searched using Hash Map is faster.

3. Binary Search

Binary Search work with ordered list by repeatly search the middle first and if not the equal then search the half part of the list that is possibly still cotains the items until the item is found or range start > range end.