solved 'Search for a Range' on LeetCode https://leetcode.com/problems/search-for-a-range/

search_range.py

class Solution(object):
    def searchRange(self, nums, target):
        """
        :type nums: List[int]
        :type target: int
        :rtype: List[int]
        """
        left = self.lowerBound(nums, target)
        if left == len(nums) or nums[left] != target:
            return (-1, -1)
        else:
            return (left, self.lowerBound(nums, target + 1) - 1)
        
    def lowerBound(self, nums, target):
        """Find the index of first element >= target."""
        lo, hi = 0, len(nums)
        while lo < hi:
            mid = (lo + hi) / 2
            if nums[mid] < target:
                lo = mid + 1
            elif nums[mid] >= target:
                hi = mid

        return lo