ZOJ 3644 Kitty's Game (记忆化搜索+hash)

const int mod = 1000000007;
vector <int> List[2001];
int num[2008];
int dp[2008][60];
int n , k , ans = 0;
map <int  , int> mp;

inline int gcd(int x , int y){
return y == 0 ? x : gcd(y , x%y);
}

inline LL lcm(int x , int y){
return (LL)x / gcd(x , y) * y;
}

int dfs(int u , int score){
int id = mp[score];
if(dp[u][id] != -1) return dp[u][id];
LL ret = 0;
for(int i = 0;i < List[u].size();i++){
int v = List[u][i];
LL LCM = lcm(score , num[v]);
if(k%LCM ||LCM == score) continue;
ret += dfs(v , LCM) , ret %= mod;
}
return dp[u][id] = ret;
}

int main()
{
int  m , k , i , j , a, b ;
while(scanf("%d%d%d",&n,&m,&k) != EOF){
for(i = 0;i <= n;i++) List[i].clear();
for(i = 0;i < m;i++){
scanf("%d%d",&a,&b) ;
List[a].push_back(b) ;
}
for(i = 1;i <= n;i++)
scanf("%d",&num[i]) ;
if(k%num
){
puts("0") ;
}
else {
List[0].push_back(1);
int id = 0 ;
mp.clear() ;
for(i = 1;i * i <= k;i++){
if(k%i == 0){
mp[i] = id++ ;
mp[k/i] = id++ ;
}
}
memset(dp , -1 , sizeof(dp)) ;
dp
[mp[k]] = 1;
cout << dfs(1 , num[1]) << endl;
}
}
return 0;
}