18.4Sum

佚名 6年前 (2019-04-08) 随笔 1102人围观抢沙发百度已收录

class Solution {
public:
    vector<vector<int>> fourSum(vector<int> &nums, int target) {
        set<vector<int>> res;
        sort(nums.begin(), nums.end());
        for (int i = 0; i < int(nums.size() - 3); ++i) {
            for (int j = i + 1; j < int(nums.size() - 2); ++j) {
                if (j > i + 1 && nums[j] == nums[j - 1]) continue;
                int left = j + 1, right = nums.size() - 1;
                while (left < right) {
                    int sum = nums[i] + nums[j] + nums[left] + nums[right];
                    if (sum == target) {
                        vector<int> out{nums[i], nums[j], nums[left], nums[right]};
                        res.insert(out);
                        ++left; --right;
                    } else if (sum < target) ++left;
                    else --right;
                }
            }
        }
        return vector<vector<int>>(res.begin(), res.end());
    }
};