72 lines
1.3 KiB
Markdown
72 lines
1.3 KiB
Markdown
---
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layout: page
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title: Search in Rotated Sorted Array
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last_solved: 2020-06-07
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category: binary search
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leetcode_url: https://leetcode.com/problems/search-in-rotated-sorted-array
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status: Attempted
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---
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Problem
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-------
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```
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Suppose an array sorted in ascending order is rotated at some pivot unknown to you beforehand.
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(i.e., [0,1,2,4,5,6,7] might become [4,5,6,7,0,1,2]).
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You are given a target value to search. If found in the array return its index, otherwise return -1.
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You may assume no duplicate exists in the array.
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Your algorithm's runtime complexity must be in the order of O(log n).
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Example 1:
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Input: nums = [4,5,6,7,0,1,2], target = 0
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Output: 4
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Example 2:
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Input: nums = [4,5,6,7,0,1,2], target = 3
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Output: -1
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```
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Solution
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----------
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Check Nick White's video on this question. it's also 2-pass binary search
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{% highlight python %}
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def search(self, nums, target):
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if not nums:
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return -1
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l,r=0,len(nums)-1
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while l<=r:
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m=(l+r)/2
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if nums[m]<nums[0]:
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r=m-1
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else:
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l=m+1
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if nums[0]>target:
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r=len(nums)-1
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else:
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l=0
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while l<=r:
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m=(l+r)/2
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if nums[m]==target:
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return m
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if nums[m]<target:
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l=m+1
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else:
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r=m-1
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return -1
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{% endhighlight %}
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![image1]() |