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
解题思路参考
先判断有序数组,然后binary search
func search(nums []int, target int) int {
if len(nums) == 0 {
return -1
}
l := 0
r := len(nums) - 1
for l+1 < r {
mid := (l + r) / 2
if target == nums[mid] {
return mid
}
if nums[l] < nums[mid] {
if target < nums[mid] && target >= nums[l] {
r = mid
} else {
l = mid
}
} else {
if target > nums[mid] && target <= nums[r] {
l = mid
} else {
r = mid
}
}
}
if nums[l] == target {
return l
}
if nums[r] == target {
return r
}
return -1
}