Closest Number in Sorted Array

Given a target number and an integer array A sorted in ascending order, find the index i in A such that A[i] is closest to the given target.

Return -1 if there is no element in the array.

Solution

class Solution:
    # @param {int[]} A an integer array sorted in ascending order
    # @param {int} target an integer
    # @return {int} an integer
    def closestNumber(self, A, target):
        if not A:
            return -1
        start, end = 0, len(A) - 1
        while start + 1 < end:
            mid = (start + end) / 2
            if A[mid] == target:
                return mid
            elif A[mid] > target:
                end = mid
            else:
                start = mid
        if A[end] - target > target - A[start]:
            return start
        else:
            return end