#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
ll dp[25][25][25];
ll func(ll a,ll b,ll c){
if(a<=0||b<=0||c<=0) return 1;
if(a>20||b>20||c>20) return func(20,20,20);
if(dp[a][b][c]>0) return dp[a][b][c];
if(a<b&&b<c) dp[a][b][c]=func(a,b,c-1)+func(a,b-1,c-1)-func(a,b-1,c);
else dp[a][b][c]=func(a-1,b,c)+func(a-1,b-1,c)+func(a-1,b,c-1)-func(a-1,b-1,c-1);
return dp[a][b][c];
}
int main()
{
ll a,b,c;
memset(dp,0,sizeof(dp));
while(scanf("%lld%lld%lld",&a,&b,&c)!=EOF){
if(a==-1&&b==-1&&c==-1) break;
printf("w(%lld, %lld, %lld) = %lld\n",a,b,c,func(a,b,c));
}
return 0;
}
记忆化搜索;
参考:https://blog.youkuaiyun.com/hjf1201/article/details/78680814