UVa 1719 Tours 2015 WF

  1 #include <cstdio>
  2 #include <cstring>
  3 #include <algorithm>
  4 #include <iostream>
  5 #include <string>
  6 #include <vector>
  7 #include <stack>
  8 #include <bitset>
  9 #include <cstdlib>
 10 #include <cmath>
 11 #include <set>
 12 #include <list>
 13 #include <deque>
 14 #include <map>
 15 #include <queue>
 16 #include <fstream>
 17 #include <cassert>
 18 #include <unordered_map>
 19 #include <unordered_set>
 20 #include <cmath>
 21 #include <sstream>
 22 #include <time.h>
 23 #include <complex>
 24 #include <iomanip>
 25 #define Max(a,b) ((a)>(b)?(a):(b))
 26 #define Min(a,b) ((a)<(b)?(a):(b))
 27 #define FOR(a,b,c) for (ll (a)=(b);(a)<(c);++(a))
 28 #define FORN(a,b,c) for (ll (a)=(b);(a)<=(c);++(a))
 29 #define DFOR(a,b,c) for (ll (a)=(b);(a)>=(c);--(a))
 30 #define FORSQ(a,b,c) for (ll (a)=(b);(a)*(a)<=(c);++(a))
 31 #define FORC(a,b,c) for (char (a)=(b);(a)<=(c);++(a))
 32 #define FOREACH(a,b) for (auto &(a) : (b))
 33 #define rep(i,n) FOR(i,0,n)
 34 #define repn(i,n) FORN(i,1,n)
 35 #define drep(i,n) DFOR(i,n-1,0)
 36 #define drepn(i,n) DFOR(i,n,1)
 37 #define MAX(a,b) a = Max(a,b)
 38 #define MIN(a,b) a = Min(a,b)
 39 #define SQR(x) ((LL)(x) * (x))
 40 #define Reset(a,b) memset(a,b,sizeof(a))
 41 #define fi first
 42 #define se second
 43 #define mp make_pair
 44 #define pb push_back
 45 #define all(v) v.begin(),v.end()
 46 #define ALLA(arr,sz) arr,arr+sz
 47 #define SIZE(v) (int)v.size()
 48 #define SORT(v) sort(all(v))
 49 #define REVERSE(v) reverse(ALL(v))
 50 #define SORTA(arr,sz) sort(ALLA(arr,sz))
 51 #define REVERSEA(arr,sz) reverse(ALLA(arr,sz))
 52 #define PERMUTE next_permutation
 53 #define TC(t) while(t--)
 54 #define forever for(;;)
 55 #define PINF 1000000000000
 56 #define newline ‘\n‘
 57 
 58 #define test if(1)if(0)cerr
 59 using namespace std;
 60 using namespace std;
 61 typedef vector<int> vi;
 62 typedef vector<vi> vvi;
 63 typedef pair<int,int> ii;
 64 typedef pair<double,double> dd;
 65 typedef pair<char,char> cc;
 66 typedef vector<ii> vii;
 67 typedef long long ll;
 68 typedef unsigned long long ull;
 69 typedef pair<ll, ll> l4;
 70 const double pi = acos(-1.0);
 71 
 72 
 73 int n, m, ans;
 74 const int maxn = 2000+1;
 75 set<int> g[maxn];
 76 
 77 int dfn[maxn], low[maxn], dfs_clcok;
 78 bool vis[maxn][maxn];
 79 vector<ii> ret;
 80 void bridges(int cur, int pa, int &times)
 81 {
 82     dfn[cur] = low[cur] = times;
 83     for (const int &nxt : g[cur])
 84     {
 85         if (nxt == pa) continue;
 86         if (!dfn[nxt])
 87         {
 88             bridges(nxt, cur, ++times);
 89             low[cur] = min(low[cur], low[nxt]);
 90             if (low[nxt] == dfn[nxt]) ret.pb(mp(cur, nxt));
 91         }
 92         else
 93             low[cur] = min(low[cur], dfn[nxt]);
 94     }
 95 }
 96 void solve()
 97 {
 98     ret.clear();
 99     Reset(dfn, 0);
100     repn(i, n) if (!dfn[i]) bridges(i, -1, dfs_clcok=1);
101     for (int i = 0; i < ret.size(); ++i)
102         vis[ret[i].first][ret[i].second] = vis[ret[i].second][ret[i].first] = true;
103 
104 }
105 int gcd(int a, int b)
106 {
107     return b?gcd(b, a%b):a;
108 }
109 int main()
110 {
111     ios::sync_with_stdio(false);
112     cin.tie(0);
113     while (cin >> n >> m)
114     {
115         Reset(vis, false);
116         repn(i, n) g[i].clear();
117         rep(i, m)
118         {
119             int u, v;   cin >> u >> v;
120             g[u].insert(v);
121             g[v].insert(u);
122         }
123         ans = -1;
124         solve();
125         for (int i = 0; i < ret.size(); ++i)
126         {
127             int u = ret[i].first, v = ret[i].second;
128             g[u].erase(v);
129             g[v].erase(u);
130         }
131         repn(i, n)
132         {
133             auto temp = g[i];
134             for (auto nxt : temp)
135             {
136                 if (vis[i][nxt]) continue;
137                 vis[i][nxt] = vis[nxt][i] = true;
138                 g[i].erase(nxt);
139                 g[nxt].erase(i);
140                 solve();
141                 if (ans == -1) ans = ret.size()+1;
142                 else ans = gcd(ans, ret.size()+1);
143                 g[i].insert(nxt);
144                 g[nxt].insert(i);
145             }
146         }
147         if (ans == -1)
148         {
149             
150             repn(i, m-1) cout << i << " ";
151             cout << m;
152             cout << newline;
153         }
154         else
155         {
156             repn(i, ans-1) if (ans % i == 0) cout << i << " ";
157             cout << ans;
158             cout << newline;
159         }
160     }
161 }
162 /*
163  4 5
164  1 2 
165  2 3 
166  3 4 
167  1 4 
168  1 3 
169  
170  6 6 
171  1 2 
172  2 3 
173  1 3 
174  1 4 
175  2 5 
176  3 6
177 */