Problem

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.

Example
For [4, 5, 1, 2, 3] and target=1, return 2.

For [4, 5, 1, 2, 3] and target=0, return -1.

思路

1. 像 find minimum in Rotated Sorted Array 那样画图,
2. 找到mid,
   1. if [mid] < [end], xxxxx
   2. else, xxxxx

    public int search(int[] A, int target) {
        if (A == null || A.length == 0) {
            return -1;
        }

        int start = 0;
        int end = A.length - 1;

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

            if (A[mid] < A[end]) {
                if (target < A[mid] || target > A[end]) {
                    end = mid;
                } else {
                    start = mid;
                }
            } else {
                if (target > A[mid] || target < A[start]) {
                    start = mid;
                } else {
                    end = mid;
                }
            }
        }
        if (A[start] == target) return start;
        if (A[end] == target) return end;
        return -1;
    }