POJ 1579

#include<stdio.h>
#include<string.h>
int d[22][22][22];
int w(int a,int b,int c){
    if(a<=0||b<=0||c<=0)
     return 1;
    else if(a>20||b>20||c>20)
     return d[20][20][20]=w(20,20,20);

    else if(d[a][b][c])
      return d[a][b][c];
    else if(a<b&&b<c)
     return d[a][b][c]=w(a, b, c-1) + w(a, b-1, c-1) - w(a, b-1, c);
    else
     return d[a][b][c]=w(a-1, b, c) + w(a-1, b-1, c) + w(a-1, b, c-1) - w(a-1, b-1, c-1) ;
     }
int main()
{
    int a,b,c;
     memset(d,0,sizeof(d));
    while(scanf("%d %d %d",&a,&b,&c),!(a==-1&&b==-1&&c==-1))
    {
      printf("w(%d, %d, %d) = %d\n",a,b,c,w(a,b,c));
    }
}