33. Search in Rotated Sorted Array

Medium
​
There is an integer array nums sorted in ascending order (with distinct values).
Prior to being passed to your function, nums is possibly rotated at an unknown pivot index k (1 <= k < nums.length) such that the resulting array is [nums[k], nums[k+1], ..., nums[n-1], nums[0], nums[1], ..., nums[k-1]] (0-indexed). For example, [0,1,2,4,5,6,7] might be rotated at pivot index 3 and become [4,5,6,7,0,1,2].
Given the array nums after the possible rotation and an integer target, return the index of target if it is in nums, or -1 if it is not in nums.
You must write an algorithm with O(log n) runtime complexity.
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
Example 3:
Input: nums = [1], target = 0
Output:
-1
Constraints:
  • 1 <= nums.length <= 5000
  • -104 <= nums[i] <= 104
  • All values of nums are unique.
  • nums is an ascending array that is possibly rotated.
  • -104 <= target <= 104

解題

Runtime: 0 ms, faster than 100%
Memory Usage: 2.5 MB, less than 100%
func search(nums []int, target int) int {
left := 0
right := len(nums) - 1
for left <= right {
mid := (left + right)/2
​
if nums[mid] == target {
return mid
}
​
if nums[mid] >= nums[left] {
if target <= nums[mid] && target >= nums[left] {
right = mid - 1
} else {
left = mid + 1
}
} else {
if target >= nums[mid] && target <= nums[right] {
left = mid + 1
} else {
right = mid - 1
}
}
}
​
return -1
}