二分查找

//递归版二分查找int binarySearch(vector<int>& nums,int left,int right,int target){    if(nums.empty()) return -1;    int mid=0;    while(left<right){        mid=(left+right)/2;        if(nums[mid]==target)        return mid;        else if(nums[mid]>target)        return binarySearch(nums,left,mid,target);        else        return binarySearch(nums,mid+1,right,target);    }    return -1;}//非递归版二分查找int binarySearch(vector<int>& nums,int left,int right,int target){    if(nums.empty()) return -1;    int mid=0;    while(left<right){        mid=(left+right)/2;        if(nums[mid]==target)        return mid;        else if(nums[mid]>target)        right=mid;        else        left=mid+1;    }    return -1;}2