[LeetCode] Problem 33 - Search in Rotated Sorted Array

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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

No.1

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

Output: 4

No.2

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

Output: -1

Code

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public int search(int[] nums, int target) {
    int left = 0;
    int right = nums.length - 1;

    while (left <= right) {
        int mid = (left + right) >> 1;

        if (nums[mid] == target)
            return mid;

        if (nums[mid] < nums[left]) {
            if (target <= nums[right] && target > nums[mid])
                left = mid + 1;
            else
                right = mid - 1;
        } else {
            if (target < nums[mid] && target >= nums[left])
                right = mid - 1;
            else
                left = mid + 1;
        }
    }

    return -1;
}