Leetcode-Solutions/15-3sum.cpp at main · aghersidev/Leetcode-Solutions · GitHub

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class Solution {
public:
    vector<vector<int>> threeSum(vector<int>& nums) {

        vector<int> nums2;
        unordered_map<int,int> freq;
        for (auto n : nums) {
            freq[n]++;
            if (freq[n] < 4) {
                nums2.push_back(n);
            }
        }
        nums = nums2;
        sort(nums.begin(), nums.end());
        vector<vector<int>> solutions;

        for (int i = 0; i < nums.size() - 2; i++) {
            int j = i + 1;
            int k = nums.size() - 1;
            while (j < k) {
                int sum = nums[i] + nums[j] + nums[k];
                if (sum == 0) {
                    vector<int> curr;
                    curr.push_back(nums[i]);
                    curr.push_back(nums[j]);
                    curr.push_back(nums[k]);
                    solutions.push_back(curr);
                    j++;
                    k--;
                } else if (sum < 0) {
                    j++;
                } else
                    k--;
            }
        }
        for (auto& c : solutions) {
            sort(c.begin(), c.end());
        }
        sort(solutions.begin(), solutions.end());
        auto it = unique(solutions.begin(), solutions.end(),
                         [](vector<int> a, vector<int> b) {
                             return ((a[1] == b[1]) && (a[2] == b[2]) &&
                                     (a[0] == b[0]));
                         });
        solutions.erase(it, solutions.end());
        return solutions;
    }
};