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33.py
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33.py
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# 33. Search in Rotated Sorted Array
# Suppose an array sorted in ascending order
# is rotated at some pivot unknown to you beforehand.
# (i.e., [0,1,2,4,5,6,7] might become [4,5,6,7,0,1,2]).
# You are given a target value to search.
# If found in the array return its index, otherwise return -1.
# You may assume no duplicate exists in the array.
# Your algorithm's runtime complexity must be in the order of O(log n).
# Example 1:
# Input: nums = [4,5,6,7,0,1,2], target = 0
# Output: 4
# Example 2:
# Input: nums = [4,5,6,7,0,1,2], target = 3
# Output: -1
from util import equal
from typing import List
def binary_search(nums: List[int], target: int) -> int:
left = 0
right = len(nums) - 1
while left <= right:
mid = left + ((right - left) >> 1)
if nums[mid] < target:
left = mid + 1
elif nums[mid] > target:
right = mid - 1
elif nums[mid] == target:
return mid
return -1
class Solution:
def search(self, nums: List[int], target: int) -> int:
left = 0
right = len(nums) - 1
while left <= right:
mid = left + ((right - left) >> 1)
if nums[mid] == target:
return mid
# nums[left:mid] is sorted
elif nums[mid] >= nums[left]:
# target in [left,mid)
if nums[mid] > target and nums[left] <= target:
flag = binary_search(nums[left:mid], target)
return left + flag if flag != -1 else flag
else:
left = mid + 1
# nums[mid:right+1] is sorted
elif nums[mid] < nums[left]:
# target in [mid,right+1)
if nums[mid] <= target and nums[right] >= target:
flag = binary_search(nums[mid:right + 1], target)
return mid + flag if flag != -1 else flag
else:
right = mid - 1
return -1
# Solution:
# Origin: 1,2,3,4,5,6,7
# Case 1: 3,4,5,6,7,1,2
# Case 2: 7,1,2,3,4,5,6
def main():
equal(Solution().search([4, 5, 6, 7, 0, 1, 2], 6), 2)
equal(Solution().search([4, 5, 6, 7, 0, 1, 2], 4), 0)
equal(Solution().search([4, 5, 6, 7, 0, 1, 2], 2), 6)
equal(Solution().search([4, 5, 6, 7, 0, 1, 2], 3), -1)
equal(Solution().search([4, 5, 6, 7, 0, 1, 2], 0), 4)
equal(Solution().search([5, 1, 3], 2), -1)
equal(Solution().search([5, 1, 3], 3), 2)
if __name__ == '__main__':
main()