leetcode#704. 二分查找

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