359B - Permutation - CodeForces Solution

#include <bits/stdc++.h>
using namespace std;

int main() {
	// your code goes here
	int n,k;
	cin>>n>>k;
	vector<int>v;
	for(int i=0;i<2*n;i++){
	    v.push_back(i+1);
	}
	int i=0;
	while(k>0){
	    swap(v[i],v[i+1]);
	    i+=2;
	    k=k-1;
	}
	for(auto x:v){
	    cout<<x<<" ";
	}cout<<endl;
	
	return 0;
}