cf B. Permutation
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
1 #include <cstdio> 2 #include <cstring> 3 #include <algorithm> 4 using namespace std; 5 6 int a[100010]; 7 int main() 8 { 9 int n,k; 10 scanf("%d%d",&n,&k); 11 for(int i=1; i<=2*n; i++) 12 { 13 a[i]=i; 14 } 15 for(int i=1; i<=k; i++) 16 { 17 swap(a[2*i-1],a[2*i]); 18 } 19 for(int i=1; i<=2*n; i++) 20 { 21 if(i==1) printf("%d",a[i]); 22 else printf(" %d",a[i]); 23 } 24 printf("\n"); 25 return 0; 26 }
http://codeforces.com/contest/359/problem/B
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
1 #include <cstdio> 2 #include <cstring> 3 #include <algorithm> 4 using namespace std; 5 6 int n,k; 7 8 int main() 9 { 10 while(scanf("%d%d",&n,&k)!=EOF) 11 { 12 printf("%d",k+1); 13 for(int i=1; i<=2*n; i++) 14 { 15 if(i!=k+1) printf(" %d",i); 16 } 17 printf("\n"); 18 } 19 return 0; 20 }