37.数字在排序数组中出现的次数(python)

题目描述

统计一个数字在排序数组中出现的次数。

# -*- coding:utf-8 -*-
class Solution:
    def GetNumberOfK(self, data, k):
        # write code here
        count = 0
        for i in range(len(data)):
            if data[i]==k:
                count+=1
        return count

二分法：

# -*- coding:utf-8 -*-
class Solution:
    def GetNumberOfK(self, data, k):
        # write code here
        def getLeftPos(data,left,right):
            while left <= right:
                mid = (left +right)//2
                if data[mid]<k:
                    left=mid+1
                else:
                    right = mid-1
            return left
        def getRightPos(data,left,right):
            while left <=right:
                mid = (left+right)//2
                if data[mid]<=k:
                    left = mid+1
                else:
                    right = mid-1
            return right
        left = 0
        right = len(data)-1
        leftPos = getLeftPos(data,left,right)
        rightPos = getRightPos(data,left,right)
        return rightPos-leftPos+1