leetcode33 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.

class Solution {
public:
    int search(vector<int>& nums, int target) {
        int a=0,b=nums.size()-1;
        while(a<=b)
        {
            int m=a+(b-a)/2;
            if(nums[m]==target)
                return m;
            if(nums[m]<nums[a])
            {
                if(nums[a]<=target)
                    b=m-1;
                else
                    a++;
            }
            else
            {
                if(nums[a]>target)
                    a=m+1;
                else if(nums[a]==target)
                    return a;
                else
                    a++;
            }
            
        }
        return -1;
    }
};