[最大环+缩点+BFS]codeforces Round 95 Div2

http://www.codeforces.com/problemset/problem/131/D

 #include<iostream>

#include<cstdio>
#include<iomanip>
#include<algorithm>
#include<cstring>
#include<string>
#include<bitset>
#include<queue>
#include<vector>
#include<string>
#include<cmath>
#include<map>
#include<set>
#define rep(i,n,m) for(int i=(n);i<=(m);++i)
#define re1(i,n) rep(i,1,n)
#define re0(i,n) rep(i,0,n)
#define RE(a) ((a)*(a))
#define SIZE(a) (int((a).size()))
#define vv(a) vector<a>
#define vi vv(int)
#define vl vv(ll)
#define vb vv(bool)
//count distance 不能用哦，已经定义了。
using namespace std;
typedef long long ll;
template<class T>
void inline maxi(T &a,T &b){
    a=max(a,b);
}
template<class T>
void inline mini(T &a,T &b){
    a=min(a,b);
}
void shownum(int n,int m){
    rep(i,n,m){
        cout<<setw(6)<<i;
    }
    cout<<endl;
}
template<class T,class P>
void fill(T &a,P v){
    int n=SIZE(a)-1;
    re0(i,n)
        a[i]=v;
}
template<class T>
void show(T &a,int n,int m){
    rep(i,n,m){
        cout<<setw(6)<<a[i];
    }
    cout<<endl;
}
template<class T>
void show(T *a[10],int n,int m){
    re0(i,n){
        re0(j,m)
            cout<<a[i]<<' ';
        cout<<endl;
    }
}
const int maxnum=3000+1;
const int maxint=2147483647;
vi G,next,dest,timee,path;
vb vis;
void addd(int a,int b){
    next.push_back(G[a]);
    G[a]=SIZE(next)-1;
    dest.push_back(b);
}
int ans,cycf,cyct;
int n;
void init(){
    scanf("%d",&n);

    G.assign(n+1,-1);
    timee.assign(n+1,0);
    vis.assign(n+1,false);
    path.assign(n+1,-1);
    ans=-1;
    re1(u,n){
        int a,b;
        scanf("%d%d",&a,&b);
        addd(a,b);
        addd(b,a);
    }
}
void dfs(int s,int t){
    vis[s]=true;
    timee[s]=t;
    for(int i=G[s];i!=-1;i=next[i]){
        int v=dest[i];
        if(!vis[v]){
            dfs(v,t+1);
            path[v]=s;
        }else{
            int tmp=timee[v]-timee[s];
            if(ans<tmp){
                ans=tmp;
                cycf=v;
                cyct=s;
            }
        }
    }
}
vi G2,next2,dest2,id;
void pp(int from,int to){
    if(to==from){
        id[from]=from;
    }
    else{
        pp(from,path[to]);
        id[to]=from;
    }
}
set<pair<int,int> > S;
void makeG(){
    G2.assign(n+1,-1);
    id.assign(n+1,0);
    S.clear();
}
void addG2(int a,int b){
    next2.push_back(G2[a]);
    G2[a] = SIZE(next2)-1;
    dest2.push_back(b);
}
int mmain(){
    init();
    dfs(1,0);
    makeG();
    re1(u,n){
        id[u]=u;
    }
    pp(cyct,cycf);
    re1(u,n){
        for(int i=G[u];i!=-1;i=next[i]){
            int v=dest[i];
            pair<int,int> p=make_pair(id[u],id[v]);
            if(p.first==p.second)
                continue;
            set<pair<int,int> >::iterator it=S.find(p);
            if(it==S.end()){
                S.insert(p);
                addG2(p.first,p.second);
            }
        }
    }
    vi final_ans(n+1,0),distt(n+1,0);
    int Q[maxnum+1];
    int head=-1,rear=0;
    Q[rear++]=cyct;
    distt[cyct]=1;
    final_ans[cyct]=distt[cyct]-1;
    while(head+1<rear){
        int tnode=Q[++head];
        for(int i=G2[tnode];i!=-1;i=next2[i]){
            int v=dest2[i];
            if(!distt[v]){
                Q[rear++]=v;
                distt[v]=distt[tnode]+1;
                final_ans[v]=distt[v]-1;
            }
        }
    }
    re1(u,n){
        printf("%d ",final_ans[u]);
    }
    puts("");
    
}
#define codeforces CODEFORCES
//#define INPUT CODEFORCES_FILE
//#define MANY_TEST CODEFORCES_MANY_TEST
const int MANY_TESST=2;
int main(){
#ifdef codeforces
    #ifdef INPUT
    freopen("input.txt","r",stdin);
    freopen("output.txt","w",stdout);
    #endif
    #ifdef MANY_TEST
    re1(wwwwwwwwwwwwwwwwwwwww,MANY_TESST)
        mmain();
    return 0;
    #endif
#endif
    mmain();
}