TheAlgorithms-Python/data_structures/arrays/search_range.py

"""
Problem: Find First and Last Position of Element in Sorted Array

Description:
Given an array of integers nums sorted in non-decreasing order, 
find the starting and ending position of a given target value.

If target is not found in the array, return [-1, -1].

Leetcode ref: 
https://leetcode.com/problems/find-first-and-last-position-of-element-in-sorted-array/
"""
from __future__ import annotations
 
def searchRange(nums: list[int], target: int) -> list[int]:
        """
        >>> searchRange([5,7,7,8,8,10],8)
        [3, 4]

        >>> searchRange([5,7,7,8,8,10],6)
        [-1, -1]

        >>> searchRange([],3)
        [-1, -1]

        >>> searchRange([5,7,8,9,9],7)
        [1, 1]
        """
        def binary_search(nums,target,left):
            low,high=0, len(nums)-1
            index=-1
            while(low<=high):
                mid=(low+high)//2
                if nums[mid]==target:
                    index=mid
                    if left:
                        high=mid-1
                    else:
                        low=mid+1
                elif nums[mid]<target:
                    low=mid+1
                else:
                    high=mid-1
            return index

        left_index=binary_search(nums,target,left=True)
        right_index=binary_search(nums,target,left=False)

        return [left_index, right_index]


if __name__ == "__main__":
    from doctest import testmod

    testmod()