[leetcode]491. Increasing Subsequences

[leetcode]491. Increasing Subsequences

---

Analysis

放假回家效率果然打折—— [每天刷题并不难0.0]

Given an integer array, your task is to find all the different possible increasing subsequences of the given array, and the length of an increasing subsequence should be at least 2 .

Explanation:

找出递增子串，用dfs解决~

Implement

class Solution {
public:
    vector<vector<int>> findSubsequences(vector<int>& nums) {
        vector<vector<int>> res;
        vector<int> tmp;
        dfs(res, tmp, nums, 0);
        return res;
    }
    void dfs(vector<vector<int>>& res, vector<int>& tmp, vector<int>& nums, int pos){
        if(tmp.size() >= 2)
            res.push_back(tmp);
        unordered_set<int> ms;
        for(int i=pos; i<nums.size(); i++){
            if((tmp.empty() || nums[i]>=tmp.back()) && ms.find(nums[i])==ms.end()){
                tmp.push_back(nums[i]);
                dfs(res, tmp, nums, i+1);
                tmp.pop_back();
                ms.insert(nums[i]);
            }
        }
    }
};