leetcode_gym/_problems/searchRotatedArray.md

layout, title, last_solved, category, leetcode_url, status

layout	title	last_solved	category	leetcode_url	status
page	Search in Rotated Sorted Array	2020-06-07	binary search	https://leetcode.com/problems/search-in-rotated-sorted-array	Attempted

Problem

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

Solution

Check Nick White's video on this question. it's also 2-pass binary search

{% highlight python %}

def search(self, nums, target): if not nums: return -1 l,r=0,len(nums)-1 while l<=r: m=(l+r)/2 if nums[m]<nums[0]: r=m-1 else: l=m+1

if nums[0]>target:
    r=len(nums)-1
else:
    l=0

while l<=r:
    m=(l+r)/2
    if nums[m]==target:
        return m
    if nums[m]<target:
        l=m+1
    else:
        r=m-1
return -1

{% endhighlight %}