Problem

Given a sorted array of integers nums in non-decreasing order and an integer target, return the index of target if it exists in the array. Otherwise, return -1.

You should solve this efficiently by narrowing the search space at each step instead of scanning the entire array.

Notes

• The array is sorted in non-decreasing order.
• If the target appears multiple times, returning any valid index is acceptable for this classic version.

Input Format

• nums: an integer array sorted in non-decreasing order
• target: an integer value to search for

Output Format

• Return the index of target if found
• Otherwise return -1

Constraints

• 0 <= nums.length
• nums is sorted in non-decreasing order
• The solution should run in logarithmic time on the size of the array

Hints

• Repeatedly compare the target with the middle element of the current range.
• After each comparison, discard the half that cannot contain the target.