_33.java

package com.fishercoder.solutions;

/**
 * Suppose a sorted array 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.
 */
public class _33 {

    public int search(int[] nums, int target) {
        if (nums == null || nums.length == 0) {
            return -1;
        }
        int minIdx = findMinIdx(nums);
        if (target == nums[minIdx]) {
            return minIdx;
        }
        int m = nums.length;
        int start = (target <= nums[m - 1]) ? minIdx : 0;
        int end = (target > nums[m - 1]) ? minIdx : m - 1;

        while (start <= end) {
            int mid = start + (end - start) / 2;
            if (nums[mid] == target) {
                return mid;
            } else if (target > nums[mid]) {
                start = mid + 1;
            } else {
                end = mid - 1;
            }
        }
        return -1;
    }

    public int findMinIdx(int[] nums) {
        int start = 0;
        int end = nums.length - 1;

        while (start < end) {
            int mid = start + (end -  start) / 2;
            if (nums[mid] > nums[end]) {
                start = mid + 1;
            } else {
                end = mid;
            }
        }
        return start;
    }

}