剑指 Offer 53 – I. 在排序数组中查找数字 I

统计一个数字在排序数组中出现的次数。

示例 1:

输入: nums = [5,7,7,8,8,10], target = 8
输出: 2

示例 2:

输入: nums = [5,7,7,8,8,10], target = 6
输出: 0

限制：

• 0 <= 数组长度 <= 50000

Python 解答：

class Solution:
    def search(self, nums: List[int], target: int) -> int:
        def findX(nums, left, right):
            if left < right:
                mid = (left+right)//2
                if nums[mid] > target:
                    return findX(nums, left, mid)
                elif nums[mid] < target:
                    return findX(nums, mid+1, right)
                else:
                    return mid
            elif nums[left] == target:
                return left
            else:
                return -1
        length = len(nums)
        if not length:
            return 0
        index = findX(nums, 0, length-1)
        if index == -1:
            return 0
        else:
            count = 0
            for i in range(index, -1, -1):
                if nums[i] == target:
                    count += 1
                else: break
            for i in range(index+1, length):
                if nums[i] == target:
                    count += 1
                else: break
        return count