Subsequences_nowcode.cpp

#include<iostream>
#include<string>
#include<vector>
#include<unordered_set>

using namespace std;

class Solution {
public:
 vector<string> generatePermutation(string s) 
 {
 int len = s.size();
 char* buf = new char[len+1];
 unordered_set<string> set;
 f(s,0,buf,0,set,len);
 vector<string> ret(set.begin(),set.end());
 delete[] buf;
 return ret;
 }
 void f(const string &s,int i,char* buf,int size,unordered_set<string> &set,int len)
 {
 if(i == len)
 {
 buf[size] = '\0';
 set.insert(buf);
 }
 else
 {
 buf[size] = s[i];
 f(s,i+1,buf,size+1,set,len);
 f(s,i+1,buf,size,set,len);
 }
 }
};


int main()
{
 string str = "aab";
 Solution s;
 vector<string> nums = s.generatePermutation(str);
 for(auto i = nums.begin();i != nums.end();++i)
 {
 cout<<*i <<"\n";
 }
}