Codeforces Beta Round #95 (Div. 2) D. Subway 【简单dfs】

#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
#include <vector>
#include <set>
#include <map>
#include <cmath>
#include <queue>
using namespace std;
template <class T> void checkmin(T &t,T x) {if(x < t) t = x;}
template <class T> void checkmax(T &t,T x) {if(x > t) t = x;}
template <class T> void _checkmin(T &t,T x) {if(t==-1) t = x; if(x < t) t = x;}
template <class T> void _checkmax(T &t,T x) {if(t==-1) t = x; if(x > t) t = x;}
typedef pair <int,int> PII;
typedef pair <double,double> PDD;
typedef long long ll;
#define foreach(it,v) for(__typeof((v).begin()) it = (v).begin(); it != (v).end ; it ++)
const int N = 3030 , M = 6060;
vector <int> g
;
int flag
;
bool vis
;
int ok;
void dfs1(int u,int f) {
if(ok) return;
vis[u] = 1;
int sz = g[u].size();
for(int i=0;i<sz;i++) {
int v = g[u][i];
if(v == f) continue;
if(vis[v]) {
flag[u] = 1;
ok = v;
return;
}
dfs1(v , u);
if(ok) {
if(ok == u) ok = -1 , flag[u] = 1;
if(ok != -1) flag[u] = 1;
return;
}
}
return;
}
void debug(int n) {
puts("debug");
for(int i=1;i<=n;i++) if(flag[i]) printf(" %d",i);
puts("end of debug");
}
int dep
;
void dfs2(int u,int f,int d) {
dep[u] = d;
int sz = g[u].size();
for(int i=0;i<sz;i++) {
int v = g[u][i];
if(v == f) continue;
if(flag[v] || dep[v]) continue;
dfs2(v , u , d + 1);
}
}
int main() {
int n;
cin >> n;
for(int i=0;i<n;i++) {
int u  , v ;
cin >>u >> v;
g[u].push_back(v);
g[v].push_back(u);
}
dfs1(1 , -1);
//debug(n);
for(int i=1;i<=n;i++) {
if(flag[i]) dfs2(i,-1,0);
}
cout << dep[1];
for(int i=2;i<=n;i++) cout << " " << dep[i];
cout << endl;
return 0;
}