Comnpute the power set of a set

readme.md

Overview

Compute the Power Set of a Set in CPP

sol1.cpp

#include <iostream>
#include <vector>
#include <string>
using namespace std;

string to_str(const vector<int>& a)
{
	string res="{"; 
	
	for(const auto& e : a) res += (res!="{"?",":"") + to_string(e); 
	
	res += "}";
	return res; 
}


string to_str(const vector<vector<int>>& a)
{
	string res; 
	for(const auto& e : a)
	{
		res += to_str(e) + "\n"; 
	}
	return res; 
}




vector<vector<int>> power_set(vector<int> a)
{
	if(a.size()==0) return {}; 
	if(a.size()==1) return {{}, a}; 
	if(a.size()>1) 
	{
		vector<vector<int>> res; 
		res.reserve(2*a.size()); 
		auto temp = power_set({a.begin(), a.end()-1}); 
		res.insert(res.end(), temp.begin(), temp.end()); 
		for(auto& e : temp) e.push_back(a[a.size()-1]); 
		res.insert(res.end(), temp.begin(), temp.end()); 
		return res; 
	}
	return {}; 
}


int main() {
	// your code goes here
	cout << to_str(power_set({1,2,3})) << endl; 
	return 0;
}