class Solution {
public:
int search(vector<int>& nums, int target) {
int ret = 0;
if (nums.size() == 0)
return -1;
if (nums[nums.size()/2] < target) {
vector<int> halfVec(nums.begin()+nums.size()/2+1,nums.end());
auto retIdx = search(halfVec,target);
if (retIdx == -1) return -1;
ret += retIdx + nums.size()/2+1;
} else if (nums[nums.size()/2] > target) {
vector<int> halfVec(nums.begin(),nums.begin()+nums.size()/2);
ret = search(halfVec,target);
} else {
ret = nums.size()/2;
}
return ret;
}
};