全TLE,求调

#include <iostream>
using namespace std;
long long f[21][21][21];
long long a,b,c,cnt;
long long w(int a1,int b1,int c1)
{
	if(f[a1][b1][c1]) return f[a1][b1][c1];
	if(a1<b1&&b1<c1){
		if(!f[a1][b1][c1-1])
			f[a1][b1][c1-1]=w(a1,b1,c1-1);
		f[a1][b1][c1]+=f[a1][b1][c1-1];
		if(!f[a1][b1-1][c1-1])
			f[a1][b1-1][c1-1]=w(a1,b1-1,c1-1);
		f[a1][b1][c1]+=f[a1][b1-1][c1-1];
		if(!f[a1][b1-1][c1])
			f[a1][b1-1][c1]=w(a1,b1-1,c1);
		f[a1][b1][c1]-=f[a1][b1-1][c1];
		return f[a1][b1][c1];
	}
	if(!f[a1-1][b1][c1]) 
		f[a1-1][b1][c1]=w(a1-1,b1,c1);
	f[a1][b1][c1]+=f[a1-1][b1][c1];
	if(!f[a1-1][b1-1][c1]) 
		f[a1-1][b1-1][c1]=w(a1-1,b1-1,c1);
	f[a1][b1][c1]+=f[a1-1][b1-1][c1];
	if(!f[a1-1][b1][c1-1]) 
		f[a1-1][b1][c1-1]=w(a1-1,b1,c1-1);
	f[a1][b1][c1]+=f[a1-1][b1][c1-1];
	if(!f[a1-1][b1-1][c1-1]) 
		f[a1-1][b1-1][c1-1]=w(a1-1,b1-1,c1-1);
	f[a1][b1][c1]-=f[a1-1][b1-1][c1-1];
	return f[a1][b1][c1];
}
int main()
{
	for(int i=0;i<=21;i++)
	for(int j=0;j<=21;j++)
	{
		f[0][i][j]=1;
		f[i][0][j]=1;
		f[i][j][0]=1;
	}
	cin>>a>>b>>c;
	while(a!=-1||b!=-1||c!=-1)
	{
		if(a<=0||b<=0||c<=0){
			cout<<"w("<<a<<','<<b<<','<<c<<") = 1"<<endl;
			continue;
		}
		if(a>20||b>20||c>20)
		{
			cout<<"w("<<a<<','<<b<<','<<c<<") = "<<w(20,20,20)<<endl;
			continue;
		}
		cout<<"w("<<a<<','<<b<<','<<c<<") = "<<w(a,b,c)<<endl;
		cin>>a>>b>>c;
	}
	return 0;
}