Search in Rotated Sorted Array

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 become4 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.

 

解题方法：

旋转数组查找，当然该题不可以自己用顺序查找的方式来查找。要充分利用旋转数组的性质。下面将给出旋转数组的类二分查找算法。

 

Code：

int Search(int A[],int n,int target){

    int low=0,high=n;

    while(low!=high){

        const int mid=(low+high)/2;

        if(A[mid]==target){

            return mid;

        }

        if(A[low]<=A[mid]){

             if(A[low]<=target && target<A[mid])

                   high=mid;

             else

                   low=mid+1;

        }else{

            if(A[mid]<target && target<=A[high-1])

                  low=mid+1;

            else

                 high=mid;

        }

    }

    return -1;

}