#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。
例子:
输入: nums = [5,7,7,8,8,10], target = 8 输出: 2
class Solution:
def search(self, nums: List[int], target: int) -> int:
#两个二分法找到左右边界
def find_left(nums, target):
l, r = 0, len(nums) - 1 #
while(l <= r):
mid = (r + l)//2
if nums[mid] < target:
l = mid + 1
elif ((mid == 0 or nums[mid - 1] < target) and nums[mid] == target):
return mid
else:
r = mid - 1
return 0
def find_right(nums, target):
l, r = 0, len(nums) - 1
while(l <= r):
mid = (r + l)//2
if nums[mid] > target:
r = mid - 1
elif ((mid == len(nums) - 1 or nums[mid + 1] > target) and nums[mid] == target):
return mid
else:
l = mid + 1
return -1
l, r = find_left(nums, target), find_right(nums, target)
return r - l + 1