代码：

#include "bits/stdc++.h"
using namespace std;
int f[30][30][30],a,b,c;
long long ak,bk,ck;
int w(int a,int b,int c){
    if(a<=0||b<=0||c<=0)return 1;
    if(f[a][b][c])return f[a][b][c];
    if(a<b&&b<c)return f[a][b][c]=w(a,b,c-1)+w(a,b-1,c-1)-w(a,b-1,c);
    return f[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(){
    while(true){
        cin>>ak>>bk>>ck;
        if(ak==-1&&bk==-1&&ck==-1)break;
        if(ak>20||bk>20||ck>20)a=b=c=20;
        else{
            a=ak;
            b=bk;
            c=ck;
        }
        cout<<"w("<<ak<<", "<<bk<<", "<<ck<<") = "<<w(a,b,c)<<endl;
    }
    return 0;
}

记录

qwq