LeetCode33 Search in Rotated Sorted Array

时间：2015-04-09 21:22:18 收藏：0 阅读：270

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.

Analysis:

Binary search

Code:

class Solution{
public:
    int search(int A[], int n, int target){
        int first = 0;
        int last = n;
        while (first != last){
            int mid = first + (last - first) / 2;
            if (A[mid] == target)
                return mid;
            if (A[first] <= A[mid]){
                if (A[first] <= target&&target < A[mid])
                    last = mid;
                else
                    first = mid + 1;
            }
            else{
                if (A[mid] < target&&target <= A[last - 1])
                    first = mid + 1;
                else
                    last = mid;
            }
        }
        return -1;
    }
};

原文：http://www.cnblogs.com/easy-busy/p/4411081.html