leetcode 15. 3Sum 二维vector

15. 3Sum

Total Accepted: 108534 Total Submissions: 584814 Difficulty: Medium

Given an array S of n integers, are there elements a, b, c in S such that a + b + c = 0? Find all unique triplets in the array which gives the sum of zero.

Note:

Elements in a triplet (a,b,c) must be in non-descending order. (ie, a ≤ b ≤ c)
The solution set must not contain duplicate triplets.

    For example, given array S = {-1 0 1 2 -1 -4},

    A solution set is:
    (-1, 0, 1)
    (-1, -1, 2)

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Submission Details

311 / 311 test cases passed.	Status: Accepted
Runtime: 76 ms	Submitted: 0 minutes ago

 1 class Solution {
 2 public:
 3     vector<vector<int>> threeSum(vector<int>& nums) {
 4         vector<vector<int>> ans;
 5         vector<int> tmp;
 6         int n = nums.size();
 7         sort(nums.begin(),nums.end());
 8         int i,j,k;
 9         for(i = 0;i < n;i++){
10             if(i != 0 && nums[i] == nums[i-1]) continue;
11             for(j = i + 1;j < n;j++){
12                 if( (j != i + 1) && (nums[j] == nums[j-1]) ) continue;
13                 for(k = j + 1;k < n;k++){
14                     if( (k != j+1 ) && (nums[k] == nums[k-1]) ) continue;
15                     if(nums[i] + nums[j] + nums[k] == 0){
16                         tmp.clear();
17                         tmp.push_back(nums[i]);tmp.push_back(nums[j]);tmp.push_back(nums[k]);
18                         ans.push_back(tmp);  
19                     }
20                 }
21             }
22         }
23         return ans;
24     }
25 };