1810630_ac_0ms_24k.c

北大大牛代码 1240道题的原代码 超级权威

# include <stdio.h>
# include <stdlib.h>

long f(int n)
{
 long result;
 if(n==0) return 1;
 if(n==2) return 3;
 result = 4*f(n-2)-f(n-4);
 return result;
}
void main()
{
 int n;
 long result;
while(1)
 {
  scanf("%d",&n);
  if(n==-1) break;
  if(n%2) {printf("0\n");continue;}
  result = f(n);
  printf("%ld\n",result);
 }
}