704. 二分查找

https://leetcode-cn.com/problems/binary-search/

解法一：二分

class Solution:
    def search(self, nums: List[int], target: int) -> int:
        left=0
        right=len(nums)-1
        while left <= right:
            mid = left + (right - left) // 2
            if nums[mid] < target:
                left = mid + 1
            elif nums[mid] > target:
                right = mid - 1
            elif nums[mid] == target:
                return mid
        return -1