leetcode-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.

思路：主要思想是二分法，两部分分别有序。（有序表的查找尽量思考二分法）

代码：

int p=0;
int q=n-1;
int mid=0;
while(p<=q)
{
mid=(p+q)/2;


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


if(A[p]<=A[mid])
{
if(A[p]<=target && A[mid]>target)
{
q=mid-1;
}
else
p=mid+1;
}
else
{
if(A[mid]<target && target<=A[q])
{
p=mid+1;
}
else
{
q=mid-1;
}
}


}
return -1;