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0491-non-decreasing-subsequences.cpp
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0491-non-decreasing-subsequences.cpp
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// class Solution {
// public:
// vector<vector<int>> findSubsequences(vector<int>& nums) {
// set<vector<int>> res;
// vector<int> curr;
// function<void(int)> go = [&](auto index) {
// if (index == nums.size()) return;
// if (curr.empty() || curr.back() <= nums[index]) curr.push_back(nums[index]);
// if (curr.size() > 1) res.insert(curr);
// go(index + 1);
// if (curr.size()) curr.pop_back();
// go(index + 1);
// };
// go(0);
// return vector<vector<int>>(res.begin(), res.end());
// }
// };
class Solution {
public:
vector<vector<int>> findSubsequences(vector<int>& nums) {
set<vector<int>> result;
vector<int> sequence;
function<void(int)> backtrack = [&](auto index) {
if (index == nums.size()) {
if (sequence.size() >= 2) result.insert(sequence);
return;
}
if (sequence.empty() || sequence.back() <= nums[index]) {
sequence.push_back(nums[index]);
backtrack(index + 1);
sequence.pop_back();
}
backtrack(index + 1);
};
backtrack(0);
return vector(result.begin(), result.end());
}
};