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| #include <iostream>
#include <string>
#include <math.h>
#include <memory.h>
using namespace std;
#define MAXSIZE 101
#define devide 1000000000
int cache[MAXSIZE][MAXSIZE][1024];
int n;
int ans_func(int last, int left,int used)
{
if(left==0)
{
if(used==1023)
return 1;
else
return 0;
}
int &ret = cache[last][left][used];
if(ret!=-1)
return ret;
if(last==0)
ret = ans_func(1,left-1,used|2);
else if(last==9)
ret = ans_func(8,left-1,used|256);
else
{
int use1 = used|(1<<(last-1));
int use2 = used|(1<<(last+1));
ret = ans_func(last-1,left-1,use1) + ans_func(last+1,left-1,use2);
}
ret %= devide;
return ret;
}
int main(void)
{
int ans=0;
cin>>n;
memset(cache,-1,sizeof(cache));
for(int i=1;i<=9;i++)
{
int use = 1<<i;
ans = (ans + ans_func(i,n-1,use))%devide;
}
cout<<ans<<endl;
}
|
