Description
Find any position of a target number in a sorted array. Return -1 if target does not exist.
Have you met this question in a real interview? Yes
Example
Given [1, 2, 2, 4, 5, 5].

For target = 2, return 1 or 2.

For target = 5, return 4 or 5.

For target = 6, return -1.
Challenge
O(logn) time

class Solution:
    """
    @param: nums: An integer array sorted in ascending order
    @param: target: An integer
    @return: An integer
    """
    def findPosition(self, nums, target):
        # write your code here
        if not nums:
            return -1
        start = 0
        end = len(nums) -1
        while (start + 1) < end:
            mid = start + (end - start)//2
            if nums[mid] == target:
                # find the last position
                end = mid
            if nums[mid] < target:
                start = mid
            else:
                end = mid
        if nums[end] == target:
            return end;
        if nums[start] ==target:
            return start
        else:
            return -1