16. 最接近的三数之和

 1 //搞清楚各个变量的含义  
 2 //***忘记对数组进行排序，以至于一直卡在这里***
 3 class Solution 
 4 {
 5 public:
 6     int threeSumClosest(vector<int>& nums, int target) 
 7     {
 8         int n = nums.size();
 9         int res = INT_MAX;//绝对值之差
10         int sum = 0;//每一组数更新的和
11         sort(nums.begin(),nums.end());
12         for(int i = 0;i < n - 2;i ++)
13         {
14             if(i > 0 && nums[i] == nums[i - 1]) continue;
15             int first = nums[i];
16             int l = i + 1;
17             int r = n - 1;
18             while(l < r)
19             {
20                 int temp1 = first + nums[l] + nums[r];//求和
21                 int temp2 = abs(first + nums[l] + nums[r] - target);//绝对值之差
22                 if(temp1 < target) l++;
23                 else if(temp1 > target) r--;
24                 else return target;
25                 if(res > temp2)
26                 {
27                     res = temp2;
28                     sum = temp1;
29                 }
30             }
31         }
32         return sum;
33     }
34 };