Solution to Leetcode 34 Find First and Last Position of Element in Sorted Array

soln_lc34.py

class Solution:
    def searchRange(self, nums: List[int], target: int) -> List[int]:
        left = self.binSearch(nums, target, True)
        right = self.binSearch(nums, target, False)
        return [left, right]
      
    # modified binary search algorithm
    def binSearch(self, nums, target, leftBiased):
        l = 0
        r = len(nums) - 1
        i = -1
        while l<=r:
            m = (l+r)//2
            if nums[m] < target:
                l = m+1
            elif nums[m] > target:
                r = m-1
            else:
                i = m
                if leftBiased:
                    r = m-1
                else:
                    l = m+1
        return i