Steward

分享是一種喜悅、更是一種幸福

程式語言 - LeetCode - C++ - 491. Non-decreasing Subsequences

---

題目：


解答：

class Solution {
public:
    vector<vector<int>> findSubsequences(vector<int>& nums) {
        int n = nums.size();
        vector<vector<int>> ans;
        vector<int> t;

        auto dfs = [&](this auto&& dfs, int start) -> void {
            if (t.size() >= 2) {
                ans.push_back(t);
            }

            unordered_set<int> used;

            for (int i = start; i < n; ++i) {
                if (used.count(nums[i])) {
                    continue;
                }

                if (!t.empty() && nums[i] < t.back()) {
                    continue;
                }

                used.insert(nums[i]);

                t.push_back(nums[i]);
                dfs(i + 1);
                t.pop_back();
            }
        };

        dfs(0);
        return ans;
    }
};