代码随想录训练营29天|●* 491.递增子序列 * 46.全排列 * 47.全排列 II

class Solution {vector<vector<int>>res;vector<int>vec;void backing(vector<int>& nums,int index){if(vec.size()>=2&&is(vec)){res.push_back(vec);}unordered_set<int> uset; // 使用set对本层元素进行去重for(int i=index;i<nums.size();i++){if(uset.find(nums[i])==uset.end()){vec.push_back(nums[i]);backing(nums,i+1);vec.pop_back();uset.insert(nums[i]);}}}bool is(vector<int>& vec){for(int i=1;i<vec.size();i++){if(vec[i]<vec[i-1])return false;}return true;}
public:vector<vector<int>> findSubsequences(vector<int>& nums) {res.clear();vec.clear();backing(nums,0);return res;}
};

class Solution {vector<vector<int>>res;vector<int>vec;void backing(vector<int>& nums,vector<bool>& used ){if(vec.size()==nums.size()){res.push_back(vec);return ;}for(int i=0;i<nums.size();i++){if(used[i]==false){   used[i]=true;        vec.push_back(nums[i]);backing(nums,used);vec.pop_back();used[i]=false;}}}
public:vector<vector<int>> permute(vector<int>& nums) {vector<bool> used(nums.size(), false);backing(nums,used);return res;}
};

class Solution {vector<vector<int>>res;vector<int>vec;void backing(vector<int>& nums,vector<bool>& used ){if(vec.size()==nums.size()){res.push_back(vec);return ;}for(int i=0;i<nums.size();i++){if (i > 0 && nums[i] == nums[i - 1] && used[i - 1] == false) {continue;}if(used[i]==false){   used[i]=true;        vec.push_back(nums[i]);backing(nums,used);vec.pop_back();used[i]=false;}}}
public:vector<vector<int>> permuteUnique(vector<int>& nums) {sort(nums.begin(), nums.end());vector<bool> used(nums.size(), false);backing(nums,used);return res;}
};