[LeetCode]15. 3Sum

class Solution {
public:
    vector<vector<int>> threeSum(vector<int>& nums) {
        int size = nums.size();
        vector<vector<int>> result;
        sort(nums.begin(), nums.end());
        for (int i = 0; i < size; i++) {
            if (nums[i] > 0) break;
            if (i > 0 && nums[i] == nums[i - 1]) continue;
            int start = i + 1;
            int end = size - 1;
            while (start < end) {
                if (nums[i] + nums[start] + nums[end] == 0) {
                    vector<int> item;
                    item.push_back(nums[i]);
                    item.push_back(nums[start]);
                    item.push_back(nums[end]);
                    result.push_back(item);
                    while (start < end && nums[start] == nums[start + 1]) start++;
                    while (start < end && nums[end] == nums[end - 1]) end--;
                    start++;
                    end--;
                } else if (nums[i] + nums[start] + nums[end] < 0) {
                    start++;
                } else {
                    end--;
                }
            }
        }
        
        return result;
    }
};