LeetCode/solutions/cpp/0015.cpp at master · SnistAheads/LeetCode · GitHub

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class Solution {
public:
    vector<vector<int>> threeSum(vector<int>& nums) {
        if (nums.size() < 3) return {};

        vector<vector<int>> ans;
        sort(nums.begin(), nums.end());

        for (int i = 0; i < nums.size() - 2; i++) {
            if (i == 0 || (nums[i] != nums[i - 1])) {
                int l = i + 1;
                int r = nums.size() - 1;
                int target = -nums[i];
                while (l < r) {
                    if (nums[l] + nums[r] == target) {
                        ans.push_back({nums[i], nums[l], nums[r]});
                        while (l < r && nums[l] == nums[l + 1]) l++;
                        while (l < r && nums[r] == nums[r - 1]) r--;
                        l++;
                        r--;
                    } else if (nums[l] + nums[r] < target) {
                        l++;
                    } else {
                        r--;
                    }
                }
            }
        }

        return ans;
    }
};