Binary Search for Target Index | Dataford Interview Questions

IDeaS G3 RMS can provide sorted forecast values for analysis. Given a sorted list of integers and a target integer, return the index of the target's first occurrence. Return -1 if the target is not present.

Your solution should use binary search rather than scanning every element.

Formal Specification

Implement search_first(nums, target).

Input: nums, a non-decreasing list of integers, and target, an integer.
Output: An integer containing the smallest index i such that nums[i] == target, or -1 when no such index exists.
Indices are zero-based.

Constraints

0 <= nums.length <= 100,000
-10^9 <= nums[i], target <= 10^9
nums is sorted in non-decreasing order
The input list is not modified

Function Signature

def search_first(nums, target):

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