题解 | #数字在升序数组中出现的次数#

import re
#
# 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
#
# 
# @param nums int整型一维数组 
# @param k int整型 
# @return int整型
#
class Solution:
    def GetNumberOfK(self , nums: List[int], k: int) -> int:
        # write code here
        len_num = len(nums)
        if len_num == 0:
            return 0
        left = 0
        right = len_num - 1
        while(left < right):
            mid = (left+right)//2
            if(nums[mid]>=k): 
                right = mid
            else:
                left = mid+1
        # 存在两种例外情况，1：left>len_num-1  2: 找到的中间值不等于k
        if left>=len_num or nums[left]!=k:
            return 0
        # 存一下左边界
        pos_left = left
        # 找右边界，因为要logn 复杂度
        # 重置一下条件
        left = 0
        right = len_num - 1 
        while(left<right):
            mid = (left+right+1)//2
            if(nums[mid]<=k):
                left = mid
            else:
                right = mid-1
        pos_right = left
        return pos_right - pos_left+1