1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141
| #include <bits/stdc++.h>
#pragma optimization_level 3 #pragma GCC optimize("Ofast,no-stack-protector,unroll-loops,fast-math,O3") #pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx") #pragma GCC optimize("Ofast") #pragma GCC target("avx,avx2,fma") #pragma GCC optimization ("unroll-loops")
using namespace std;
struct PairHash {inline std::size_t operator()(const std::pair<int, int> &v) const { return v.first * 31 + v.second; }};
#define Code ios_base::sync_with_stdio(false); #define By ios::sync_with_stdio(0); #define Sumfi cout.tie(NULL);
using ll = long long; using ld = long double; using ull = unsigned long long;
const ld PI = 3.14159265358979323846; const ll INF = 1e18; const ld EPS = 1e-9; const ll MAX_N = 40404; const ll mod = 1e9 + 7;
typedef pair<ll, ll> pll; typedef vector<pll> vpll; typedef array<ll,3> all3; typedef array<ll,5> all5; typedef vector<all3> vall3; typedef vector<all5> vall5; typedef vector<ld> vld; typedef vector<ll> vll; typedef vector<vll> vvll; typedef vector<int> vi; typedef pair<string, string> pss; typedef vector<pss> vpss; typedef vector<string> vs; typedef vector<vs> vvs; typedef unordered_set<ll> usll; typedef unordered_set<pll, PairHash> uspll; typedef unordered_map<ll, ll> umll; typedef unordered_map<pll, ll, PairHash> umpll;
#define rep(i,m,n) for(ll i=m;i<n;i++) #define rrep(i,m,n) for(ll i=n;i>=m;i--) #define all(a) begin(a), end(a) #define rall(a) rbegin(a), rend(a) #define ZERO(a) memset(a,0,sizeof(a)) #define MINUS(a) memset(a,0xff,sizeof(a)) #define ASCEND(a) iota(all(a),0) #define sz(x) ll((x).size()) #define pyes cout<<"YES\n"; #define pno cout<<"NO\n"; #define pneg1 cout<<"-1\n"; #define CASE(x) cout<<"Case #"<<x<<": ";
template <typename T> void print(T &&t) { cout << t << "\n"; } template<typename T> void printv(vector<T>v){ll n=v.size();rep(i,0,n)cout<<v[i]<<" ";cout<<"\n";} void fileIO() {freopen("input.txt","r",stdin); freopen("output.txt","w",stdout);}
ll __gcd(ll x, ll y) { return !y ? x : __gcd(y, x % y); } ll __lcm(ll x, ll y) { return x * y / __gcd(x,y); } ll modpow(ll n, ll x, ll MOD = mod) { if(!x) return 1; ll res = modpow(n,x>>1,MOD); res = (res * res) % MOD; if(x&1) res = (res * n) % MOD; return res; }
vll adj[55]; ll id = 1; ll mi[55], vis[55]; vvll st; vector<vvll> bcc;
void dfs(ll u, ll par) { mi[u] = vis[u] = id++; for(auto& v : adj[u]) { if(v == par) continue; if(vis[u] > vis[v]) st.push_back({u,v});
if(vis[v]) mi[u] = min(mi[u], vis[v]); else { dfs(v,u); mi[u] = min(mi[u], mi[v]); if(mi[v] >= vis[u]) { bcc.emplace_back(); while(!st.empty()) { auto e = st.back(); st.pop_back(); bcc.back().push_back(e); if(e[0] == u and e[1] == v) break; } } } } }
ll solve(vpll& E, ll n) { rep(i,0,sz(E)) { auto [u,v] = E[i]; adj[u].push_back(v); adj[v].push_back(u); } rep(i,1,n+1) { if(!vis[i]) dfs(i,-1); }
ll res = 0; rep(i,0,sz(bcc)) { res += sz(bcc[i]) == 1; }
return res; }
int main() { Code By Sumfi
cout.precision(12);
ll tc = 1; rep(i,1,tc+1) { ll n,m; cin>>n>>m; vpll A(m); rep(i,0,m) cin>>A[i].first>>A[i].second; print(solve(A,n)); }
return 0; }
|