题目链接：


Function Run Fun


Time Limit: 1000MS

 

Memory Limit: 10000K

Total Submissions: 18356

 

Accepted: 9386


Description


We all love recursion! Don't we? 

Consider a three-parameter recursive function w(a, b, c): 

if a <= 0 or b <= 0 or c <= 0, then w(a, b, c) returns: 
1 

if a > 20 or b > 20 or c > 20, then w(a, b, c) returns: 
w(20, 20, 20) 

if a < b and b < c, then w(a, b, c) returns: 
w(a, b, c-1) + w(a, b-1, c-1) - w(a, b-1, c) 

otherwise it returns: 
w(a-1, b, c) + w(a-1, b-1, c) + w(a-1, b, c-1) - w(a-1, b-1, c-1) 

This is an easy function to implement. The problem is, if implemented directly, for moderate values of a, b and c (for example, a = 15, b = 15, c = 15), the program takes hours to run because of the massive recursion. 


Input


The input for your program will be a series of integer triples, one per line, until the end-of-file flag of -1 -1 -1. Using the above technique, you are to calculate w(a, b, c) efficiently and print the result.


Output


Print the value for w(a,b,c) for each triple.


Sample Input


1 1 1 2 2 2 10 4 6 50 50 50 -1 7 18 -1 -1 -1


Sample Output


w(1, 1, 1) = 2 w(2, 2, 2) = 4 w(10, 4, 6) = 523 w(50, 50, 50) = 1048576 w(-1, 7, 18) = 1



#include<cstdio>
#include<algorithm>
#include<cstring>
#define LL long long
using namespace std;
LL a,b,c;
LL w[30][30][30];
int main()
{
  for(int i=0;i<=20;i++)
  {
    for(int j=0;j<=20;j++)
    {
      for(int k=0;k<=20;k++)
      {
        if(!i||!j||!k)  w[i][j][k]=1;
        else if(i<j&&j<k)
          w[i][j][k]=w[i][j][k-1]+w[i][j-1][k-1]-w[i][j-1][k];
        else
          w[i][j][k]=w[i-1][j][k]+w[i-1][j-1][k]+w[i-1][j][k-1]-w[i-1][j-1][k-1];
      }
    }
  }
  while(~scanf("%lld%lld%lld",&a,&b,&c))
  {
    if(a==-1&&b==-1&&c==-1)  break;
    LL ans;
    if(a<=0||b<=0||c<=0)
      ans=1;
    else if(a>20||b>20||c>20)
      ans=w[20][20][20];
    else
      ans=w[a][b][c];
    printf("w(%lld, %lld, %lld) = %lld\n",a,b,c,ans);
  }
  return 0;
}