好难啊。

我之前尝试用递归失败了， 最后写了个循环的

class Solution:
    def upper_bound_(self , n , v , a ):
        # write code here
        low, high = 0 , n-1
        res = n + 1
        while low <= high:
            mid = (high - low) // 2 + low
            num = a[mid]
            if num < v:   
                # 往右边移动
                low = mid + 1
            else:
                high = mid - 1
                res = mid + 1
        return res