python 二分查

class Solution:
    """
    @param nums: The integer array.
    @param target: Target to find.
    @return: The first position of target. Position starts from 0.
    """
    def find_target(self, nums, target) :
        result = nums.index(target)
        return result

    def binarySearch(self, nums, target) :
        # write your code here
        length = len(nums)
        if length % 2 == 0 :
            if target in nums[:int(length / 2)] :
                return self.find_target(nums[:int(length / 2)], target)
            elif target in nums[int(length / 2) :] :
                return int(length / 2) + self.find_target(nums[int(length / 2) :], target)
            else :
                return -1

        elif length % 2 == 1 :
            if target in nums[:int((length - 1) / 2) + 1] :
                return self.find_target(nums[:int((length - 1) / 2) + 1], target)
            elif target in nums[int((length - 1) / 2) + 1 :] :
                return int((length - 1) / 2) + 1 + self.find_target(nums[int((length - 1) / 2) + 1 :], target)
            else :
                return -1