leetcode 15. 3Sum 二维vector

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15. 3Sum

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Question

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

 

 

class Solution {
public:
    vector<vector<int>> threeSum(vector<int>& nums) {
        vector<vector<int>> ans;
        vector<int> tmp;
        int n = nums.size();
        sort(nums.begin(),nums.end());
        int i,j,k;
        for(i = 0;i < n;i++){
            if(i != 0 && nums[i] == nums[i-1]) continue;
            for(j = i + 1;j < n;j++){
                if( (j != i + 1) && (nums[j] == nums[j-1]) ) continue;
                for(k = j + 1;k < n;k++){
                    if( (k != j+1 ) && (nums[k] == nums[k-1]) ) continue;
                    if(nums[i] + nums[j] + nums[k] == 0){
                        tmp.clear();
                        tmp.push_back(nums[i]);tmp.push_back(nums[j]);tmp.push_back(nums[k]);
                        ans.push_back(tmp);  
                    }
                }
            }
        }
        return ans;
    }
};