LeetCode 491. 递增的子序列

题目描述链接：https://leetcode-cn.com/problems/increasing-subsequences/

基本思路：DFS+哈希

LeetCode C++ 求解代码：

class Solution {
public:
    set<vector<int>> record;
    vector<vector<int>>res;
    
    vector<vector<int>> findSubsequences(vector<int>& nums) {
         
         
         for(int i=0;i<nums.size();i++){
             vector<int>ans;
             ans.push_back(nums[i]);
             dfs(nums,i,i,ans);
         }
         return res;
        }

    void dfs(vector<int>&nums,int i,int j,vector<int>ans){
        if(j==nums.size()){
            return ;//递归结束条件
        }
        bool flag=0;
        if(i<j){
              for(int k=0;k<ans.size();k++){
                  if(ans[k]>nums[j]){
                     flag=1;
                  }
              }
              if(!flag){
                  ans.push_back(nums[j]);
                 if(record.find(ans)==record.end()){
                  res.push_back(ans);
                  record.insert(ans);
                }
              }

              
        }
        for(int x=j+1;x<nums.size();x++){
            dfs(nums,i,x,ans);
        }
       if(!flag) ans.pop_back();
    }

};