Series-Parallel Networks UVA - 10253

#include<bits/stdc++.h>
using namespace std;

#define rep(i,a,b) for(int i=a;i<b;i++)
#define per(i,a,b) for(int i=b-1;i>=a;i--)

typedef long long ll;

const int maxn=40;
ll dp[maxn][maxn];

ll C(ll n,ll m){//爆了int,绝望.jpg,多校忘了取模,简直是条咸鱼了
    ll ans=1;
    for(int i=1;i<=m;i++){
        ans=ans*(n-i+1)/i;
    }
    return ans;
}

ll dfs(int n,int m){
    ll& ans=dp[n][m];
    if(m==1)return ans=1;
    if(ans!=-1)return ans;
    ans=0;
    for(int i=0;i*m<=n;i++){
        ans+=C(dfs(m,m-1)+i-1,i)*dfs(n-i*m,m-1);
    }
    return ans;
}

int main(){
    int n;
    while(scanf("%d",&n)==1&&n){
        memset(dp,-1,sizeof(dp));
        dp[1][1]=1;
        if(n==1){
            printf("1\n");
            continue;
        }
        ll ans=dfs(n,n-1);
        printf("%lld\n",2ll*ans);
    }
    return 0;
}

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转载自blog.csdn.net/qq_36424540/article/details/81673856