Java Search Algorithms

    1.Linear search or sequential search is a method for finding a particular value in a list that consists of checking every one of its elements, one at a time and in sequence, until the desired one is found.

   ·Linear search is the simplest search algorithm. For a list with n items, the best case is when the value is equal to the first element of the list, in which case only one comparison is needed. The worst case is when the value is not in the list (or occurs only once at the end of the list), in which case n comparisons are needed.

    ·Linear searches don't require the collection to be sorted.

    2. A binary search or half-interval search algorithm finds the position of a specified value (the input "key") within a sorted array. In each step, the algorithm compares the input key value with the key value of the middle element of the array. If the keys match, then a matching element has been found so its index, or position, is returned. Otherwise, if the sought key is less than the middle element's key, then the algorithm repeats its action on the sub-array to the left of the middle element or, if the input key is greater, on the sub-array to the right. If the remaining array to be searched is reduced to zero, then the key cannot be found in the array and a special "Not found" indication is returned.

    · Every iteration eliminates half of the remaining possibilities. This makes binary searches very efficient - even for large collections.

   · Binary search requires a sorted collection. Also, binary searching can only be applied to a collection that allows random access (indexing).

   ·Worst case performance: O(log n)

    · Best case performance: O(1)