Q. Describe the basic concept of binary search technique? Is it more efficient than the sequential search?        

Ans:

The binary search technique:-

This technique is applied to an ordered list where elements are arranged either in ascending order or descending order. The array is divided into two parts and the item being searched for is compared with item at the middle of the array. If they are equal the search is successful. Otherwise the search is performed in either the first half or second half of the array. If the middle element is greater than the item being searched for the search process is repeated in the first half of the array otherwise the process is repeated in the second half of the array. Each time a comparison is made, the number of element yet to be searched will be cut in half. Because of this division of array into two equal parts, the method is called a binary search.

In binary search, each iteration of the loop halves the size of the list to be searched. Thus the maximum number of key comparisons is approximately

2*log2n. This is quite an improvement over the sequential search, chiefly as the list gets larger. The binary search is, however, not guaranteed to be quicker for searching for small lists. Even though the binary search needs less number of comparisons, each comparison needs more computation or calculation. When n is small, the constant of proportionality can dominate. Therefore, in case of fewer number of elements in the list, a sequential search is enough.