#include <iostream>
#include <cstdio>
#define ri register
using namespace std;
int dp[31];
int main(){
ri int i(2),j,n;dp[0]=1;
while(scanf("%d",&n),n!=-1){
while(i<=n){
dp[i]+=dp[i-2]*3;
for(j=4;j<=i;++j)dp[i]+=dp[i-j]*2;
i+=2;
}
printf("%d\n",dp[n]);
}
return 0;
}
8 条评论
-
a1b3c7d9 LV 7 @ 2018-12-06 13:21:53
-
@ 2018-12-06 13:20:51
-
@ 2018-12-01 08:13:05
在吗
-
@ 2018-12-01 08:11:31
在吗
-
@ 2018-12-01 08:07:33
在吗
-
@ 2018-11-25 15:59:44
-
@ 2018-11-22 14:01:26
#include <iostream>
#include <cstdio>
#include <ctime>
#define il inline
using namespace std;
il int random(int,int);
int main(){
srand(time(NULL));return 0;
}
il int random(int l,int r){
return rand()%(r-l)+l;
} -
@ 2018-11-17 17:13:45
#include <iostream>
#include <cstdio>
using namespace std;
int n,a[500001],c[500001];long long ans(0);
inline void read(int&),mergesort(int,int);
int main(){
read(n);//n num
int h;
for(h=1;h<=n;++h)read(a[h]);
mergesort(1,n);
printf("%lld",ans);
return 0;
}
inline void read(int &x){
x=0;char c(getchar());bool check(false);
while(c==' '||c=='\n')c=getchar();
if(c=='-')check=true,c=getchar();
while(c>='0'&&c<='9')x=x*10+c-'0',c=getchar();
if(check)x=-x;
}
inline void mergesort(int l,int r){
if(l==r)return;
int mid((l+r)>>1),i(l),j(mid+1),k(l);
mergesort(l,mid),mergesort(j,r);
while(i<=mid&&j<=r)
if(a[i]<=a[j])c[k]=a[i],++i,++k;
else c[k]=a[j],++j,++k,ans+=mid-i+1;
while(i<=mid)c[k]=a[i],++i,++k;
while(j<=r)c[k]=a[j],++j,++k;
for(i=l;i<=r;++i)a[i]=c[i];
}
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