LeetCode | Search in Rotated Sorted Array

题目

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.
分析
在二分查找的基础上，总结出旋转数组会对首尾指针的移动造成哪些改变，体现在在代码里即可。

代码

public class SearchInRotatedSortedArray {
public int search(int[] A, int target) {
if (A == null || A.length == 0) {
return -1;
}
int low = 0;
int high = A.length - 1;
while (low <= high) {
int mid = low + (high - low) / 2;
if (target == A[mid]) {
return mid;
} else if (target < A[mid]) {
if (A[mid] > A[high] && target < A[low]) {
low = mid + 1;
} else {
high = mid - 1;
}
} else {
if (A[mid] < A[low] && target > A[high]) {
high = mid - 1;
} else {
low = mid + 1;
}
}
}
return -1;
}
}