33. Search in Rotated Sorted Array

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.

Solution

public class Solution {
 public int search(int[] nums, int target) {
        int start = 0;
        int end = nums.length - 1;

        while (start + 1 < end) {
            int middle = start + (end - start) / 2;

            if (nums[middle] == target ) {
                return middle;
            } else if (nums[middle] > nums[end]) {
                if (target >= nums[start] && target < nums[middle]) {
                    end = middle;
                } else {
                    start = middle;
                }
            } else {
                if (target <= nums[end] && target > nums[middle] ) {
                    start = middle;
                } else {
                    end = middle;
                }
            }
        }

        if (nums[start] == target) {
            return start;
        } else if (nums[end] == target) {
            return end;
        } else {
            return -1;
        }
    }
}