Leetcode 540. 有序数组中的单一元素（DAY 181）---- 二分查找学习期

• • 原题题目
  • 代码实现（首刷自解 二分查找）

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

    int singleNonDuplicate(vector& nums) 
    {
        int ret = 0,left = 0,right = nums.size()-1;
        while(left < right)
        {
            int pos = my_lower_bound(nums,nums[(left+right)/2]);
            int size = (pos - left);
            if(!(size % 2)) 
            {
                if(left == pos) left += 2;
                else    left = pos;
            }
            else    right = pos - 1;
        }
        return nums[left];
    }
};