SGU 134 数组模拟树状dp

往往在dfs层数增加的时候都会面临着爆栈的危险，怎样避免它？？栈模拟？不对~栈模拟编程复杂度太高~

用数组模拟！数组模拟不仅快，而且代码量很短~适合搞树状dp~细节多，初学者慎用~

#include<iostream>
#include<vector>
#include<algorithm>
#include<cstdio>
#include<queue>
#include<stack>
#include<string>
#include<map>
#include<set>
#include<cmath>
#include<cassert>
#include<cstring>
#include<iomanip>
using namespace std;

#ifdef _WIN32
#define i64 __int64
#define out64 "%I64d\n"
#define in64 "%I64d"
#else
#define i64 long long
#define out64 "%lld\n"
#define in64 "%lld"
#endif

#define FOR(i,a,b)      for( int i = (a) ; i <= (b) ; i ++)
#define FF(i,a)         for( int i = 0 ; i < (a) ; i ++)
#define FFD(i,a)        for( int i = (a)-1 ; i >= 0 ; i --)
#define S64(a)          scanf(in64,&a)
#define SS(a)           scanf("%d",&a)
#define LL(a)           ((a)<<1)
#define RR(a)           (((a)<<1)+1)
#define SZ(a)           ((int)a.size())
#define PP(n,m,a)       puts("---");FF(i,n){FF(j,m)cout << a[i][j] << ' ';puts("");}
#define pb              push_back
#define CL(Q)           while(!Q.empty())Q.pop()
#define MM(name,what)   memset(name,what,sizeof(name))
#define read            freopen("in.txt","r",stdin)
#define write           freopen("out.txt","w",stdout)

const int inf = 0x3f3f3f3f;
const i64 inf64 = 0x3f3f3f3f3f3f3f3fLL;
const double oo = 10e9;
const double eps = 10e-10;
const double pi = acos(-1.0);
const int maxn = 16001;

vector<int>g[maxn];
vector<int>v;
int dp[maxn];
int dpmax[maxn];
int f[maxn];
int dfn[maxn];  
int dfv[maxn];
int df,n,ans;


void dfs(int now=1)
{
    FF(i,g[now].size()) if(g[now][i] != f[now])
    {
        f[g[now][i]] = now;
        dfs(g[now][i]);
    }
    dfv[df] = now;
    dfn[now] = df;
    df++;
    return ;
}

void dps()
{
    FOR(i,1,df-2)    // 这个地方小心，-1的话就是wa，因为根节点没有父节点
    {
        dp[dfv[i]]++;
        dpmax[dfv[i]]=max(dpmax[dfv[i]],n-dp[dfv[i]]);
        dpmax[f[dfv[i]]]=max(dpmax[f[dfv[i]]],dp[dfv[i]]);
        dp[f[dfv[i]]]+=dp[dfv[i]];
    }
    return ;
}

void start()
{
    df = 1;
    MM(dp,0);
    MM(dpmax,0);
    MM(f,0);
    dfs();
    dps();
    ans=inf;
    for(int i=1;i<=n;i++)
    {
        ans = min(ans,dpmax[i]);
    }
    for(int i=1;i<=n;i++)
    {
        if(dpmax[i] == ans)
        {
            v.pb(i);
        }
    }
    sort(v.begin(),v.end());
    return ;
}

int main()
{
    cin>>n;
    int now,to;
    FOR(i,1,n-1)
    {
        cin>>now>>to;
        g[now].pb(to);
        g[to].pb(now);
    }
    start();
    cout<<ans<<" "<<v.size()<<endl;
    FF(i,v.size()-1)
    {
        cout<<v[i]<<" ";
    }
    cout<<v.back()<<endl;
    return 0;
}