给自己看
class Solution:
    def search(self , nums: List[int], target: int) -> int:
        
        if target in nums:
            left = 0
            right = len(nums)-1
            while left!=right:
                if nums[int((left+right)/2)]>target:
                    right = int((left+right)/2)-1
                elif nums[int((left+right)/2)]==target:
                    left = int((left+right)/2)
                    break
                else:
                    left = int((left+right)/2)+1
            return left
        else:
            return -1