c# - Extension of Binary search algo to find the first and last index of the key value to be searched in an array

Question

The problem is to extend the binary search algorithm to find all occurrences of a target value in a sorted array in the most efficient way. Concretely speaking, the input of the algorithm is (1) a sorted array of integers, where some numbers may appear more than once, and (2) a target integer to be searched. The output of the algorithm should be a pair of index values, indicating the first and last occurrence of the integer in the array, if it does occur. The source code could be in c#, c, c++.

Also, what is the max and min number of comparisons that we might need to find the indexes?

Answer 1

For C++, you could look up std::equal_range() and its complexity requirements. As long as you're interested in the basic algorithm, the same general rules should apply regardless of the language use for the implementation.