Search in Rotated Sorted Array

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.

Notes:

1. Find the increase section firstly, compare A[start] and A[middle]
2. And then judge target is in this section or not

    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 middle = start + (end-start)/2;

            if (A[middle] == target) {
                return middle;
            } else if (A[start] < A[middle]) {
                // start .. middle increase
                if (A[start] <= target && target <= A[middle]) {
                    end = middle;
                } else {
                    start = middle;
                }
            } else {
                // middle .. end increase
                if (A[middle] <= target && target <= A[end]) {
                    start = middle;
                } else {
                    end = middle;
                }
            }
        }

        if (A[start] == target) {
            return start;
        }

        if (A[end] == target) {
            return end;
        }

        return -1;
    }