LeetCode

LeetCode_3Sum

 1 class Solution {
 2 public:
 3     vector<vector<int> > threeSum(vector<int> &num) {
 4         // Start typing your C/C++ solution below
 5         // DO NOT write int main() function
 6         vector<vector<int> > output; 
 7         if(num.size()<3) return output; 
 8          
 9         sort(num.begin(), num.end());
10         
11         for(int i =0; i< num.size() -2 ;){
12             int startS = i + 1 ;
13             int endS = num.size() - 1 ;
14             while(startS < endS){
15              
16              int sum = num[i] + num[startS] + num[endS];
17              if(sum == 0) {
18                     vector<int> triplet;  
19                     triplet.push_back(num[i]);  
20                     triplet.push_back(num[startS]);  
21                     triplet.push_back(num[endS]);  
22                     output.push_back(triplet);  
23                     startS++ ;
24                     while(num[startS] == num[startS-1] && startS < endS) startS++;
25              }
26              if(sum < 0)
27                    startS ++;
28              else
29                     endS --;    
30             }   
31             i++;
32             while(num[i] == num[i-1] && i< num.size() -2) i ++;     
33         }        
34         return output;
35     }
36 };

和3Sum closest 类似，注意删除重复的三元组就行

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