July_leetcode_challenge/3sum.cpp at main · Harshdeep-Yadav/July_leetcode_challenge · GitHub

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class Solution {
public:
    vector<vector<int>> threeSum(vector<int>& nums) {
       vector<vector<int>> res;
        sort(nums.begin(), nums.end());

        // moves for a
        for (int i = 0; i < (int)(nums.size())-2; i++)
        {

            if (i == 0 || (i > 0 && nums[i] != nums[i-1])) {

                int lo = i+1, hi = (nums.size())-1, sum = 0 - nums[i];

                while (lo < hi) {
                    if (nums[lo] + nums[hi] == sum) {

                        vector<int> temp;
                        temp.push_back(nums[i]);
                        temp.push_back(nums[lo]);
                        temp.push_back(nums[hi]);
                        res.push_back(temp);

                        while (lo < hi && nums[lo] == nums[lo+1]) lo++;
                        while (lo < hi && nums[hi] == nums[hi-1]) hi--;

                        lo++; hi--;
                    }
                    else if (nums[lo] + nums[hi] < sum) lo++;
                    else hi--;
               }
            }
        }
        return res;

    }
};