StarWalker

Where my heart will take me

0%

Leetcode033-searchInRotatedSortedArray

Posted on Edited on In Views: Valine:
Solution Report of LeetCode Acceptted

Description

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

Example 1:

1
2
Input: nums = [4,5,6,7,0,1,2], target = 0
Output: 4

Example 2:
1
2
Input: nums = [4,5,6,7,0,1,2], target = 3
Output: -1

Solution

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
class Solution {
    public int search(int[] nums, int target) {
        if (nums == null || nums.length == 0) return -1;

        int left = 0;
        int right = nums.length -1;
        while (left <=right){
            int mid = left + (right - left)/2;
            if (nums[mid] == target) return mid;
            
            if (nums[mid] <= nums[right]){
                if (target > nums[mid] && target <= nums[right]) left = mid + 1;
                else right = mid -1;
            }
            else{
                if (target >= nums[left] && target < nums[mid]) right = mid - 1;
                else left = mid + 1;
            }
        }
        return -1;
    }
}