0491 solved.

liuyubobobo · liuyubobobo · commit 4c98a35c8af6 · 2023-01-19T23:26:27.000-08:00
diff --git a/0001-0500/0491-Non-decreasing-Subsequences/cpp-0491/CMakeLists.txt b/0001-0500/0491-Non-decreasing-Subsequences/cpp-0491/CMakeLists.txt
@@ -0,0 +1,6 @@
+cmake_minimum_required(VERSION 3.24)
+project(cpp_0491)
+
+set(CMAKE_CXX_STANDARD 17)
+
+add_executable(cpp_0491 main.cpp)
diff --git a/0001-0500/0491-Non-decreasing-Subsequences/cpp-0491/main.cpp b/0001-0500/0491-Non-decreasing-Subsequences/cpp-0491/main.cpp
@@ -0,0 +1,49 @@
+/// Source : https://leetcode.com/problems/non-decreasing-subsequences/description/
+/// Author : liuyubobobo
+/// Time   : 2023-01-19
+
+#include <iostream>
+#include <vector>
+#include <set>
+
+using namespace std;
+
+
+/// Backtrack
+/// Time Compelxity: O(2^n)
+/// Space Compelxity: O(n)
+class Solution {
+public:
+    vector<vector<int>> findSubsequences(vector<int>& nums) {
+
+        int n = nums.size();
+        set<vector<int>> res;
+        vector<int> cur;
+        dfs(n, nums, 0, cur, res);
+        return vector<vector<int>>(res.begin(), res.end());
+    }
+
+private:
+    void dfs(int n, const vector<int>& nums, int start,
+             vector<int>& cur, set<vector<int>>& res){
+
+        if(start == n){
+            if(cur.size() >= 2) res.insert(cur);
+            return;
+        }
+
+        dfs(n, nums, start + 1, cur, res);
+
+        if(cur.empty() || nums[start] >= cur.back()){
+            cur.push_back(nums[start]);
+            dfs(n, nums, start + 1, cur, res);
+            cur.pop_back();
+        }
+    }
+};
+
+
+int main() {
+
+    return 0;
+}
diff --git a/readme.md b/readme.md
@@ -522,7 +522,7 @@ email: [liuyubobobo@gmail.com](mailto:liuyubobobo@gmail.com)
 | 488 | [Zuma Game](https://leetcode.com/problems/zuma-game/) | [无] | [C++](0001-0500/0488-Zuma-Game/cpp-0488/) | | |
 | 489 | [Robot Room Cleaner](https://leetcode.com/problems/robot-room-cleaner/) | [solution](https://leetcode.com/problems/robot-room-cleaner/solution/) | [C++](0001-0500/0489-Robot-Room-Cleaner/cpp-0489/) | | |
 | 490 | [The Maze](https://leetcode.com/problems/the-maze/description/) | [solution](https://leetcode.com/problems/the-maze/solution/) | [C++](0001-0500/0490-The-Maze/cpp-0490/) | | |
-| | | | | | |
+| 491 | [Non-decreasing Subsequences](https://leetcode.com/problems/non-decreasing-subsequences/description/) | [无] | [C++](0001-0500/0491-Non-decreasing-Subsequences/cpp-0491/) | | |
 | 492 | [Construct the Rectangle](https://leetcode.com/problems/construct-the-rectangle/) | [无] | [C++](0001-0500/0492-Construct-the-Rectangle/cpp-0492/) | | |
 | | | | | | |
 | 494 | [Target Sum](https://leetcode.com/problems/target-sum/description/) | [solution](https://leetcode.com/problems/target-sum/solution/) | [C++](0001-0500/0494-Target-Sum/cpp-0494/) | | |
