题目描述

blablabla

样例

class Solution(object):
    def getNumberOfK(self, nums, k):
        """
        :type nums: list[int]
        :type k: int
        :rtype: int
        """
        if len(nums) <= 0:
            return 0
        if len(nums) == 1:
            return 1 if nums[0] == k else 0
        # 二分搜索    
        left, right = 0, len(nums) - 1
        while right > left + 1:
            mid = left + (right - left) // 2

            if nums[mid] >= k:
                right = mid
            else:
                left = mid

        if nums[right] == k:
            mid = right
        if nums[left] == k:
            mid = left
        # 得到mid    
        if nums[mid] == k:
            count = 0
            left, right = mid, mid
            while left >= 0 and nums[left] == k:
                count += 1
                left -= 1
            while right < len(nums) and nums[right] == k:
                count += 1
                right += 1
            return count - 1
        else:
            return 0