poj1579

/*简单递推*/#include<stdio.h>#include<string.h>int a[21][21][21];int main(){int i,j,n,m,k;memset(a,0,sizeof(a));for(i=0;i<=20;i++)for(j=0;j<=20;j++)for(k=0;k<=20;k++){if(i==0||j==0||k==0) a[i][j][k]=1;else{    if(i<j && j<k){a[i][j][k]=a[i][j][k-1]+a[i][j-1][k-1]-a[i][j-1][k];}   else      a[i][j][k]=a[i-1][j][k]+a[i-1][j-1][k]+a[i-1][j][k-1]-a[i-1][j-1][k-1];}}int A,B,C;while(scanf("%d%d%d",&A,&B,&C)!=EOF){if(A==-1 && B==-1 && C==-1) break;if(A<0 || B<0 || C<0)    { printf("w(%d, %d, %d) = %d\n",A,B,C,a[0][0][0]); continue;}if(A>20 || B>20 || C>20)  { printf("w(%d, %d, %d) = %d\n",A,B,C,a[20][20][20]); continue;}    printf("w(%d, %d, %d) = %d\n",A,B,C,a[A][B][C]);}      return 0;}