[AtCoder] E - Graph Destruction

E - Graph Destruction

  • Time : O(elogv)
  • Space : O(v)
c++
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#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")//Comment optimisations for interactive problems (use endl)
#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; }
};

// speed
#define Code ios_base::sync_with_stdio(false);
#define By ios::sync_with_stdio(0);
#define Sumfi cout.tie(NULL);

// alias
using ll = long long;
using ld = long double;

// constants
const ld PI = 3.14159265358979323846; /* pi */
const ll INF = 987654321;
const ld EPS = 1e-9;
const ll MAX_N = 202020;

// typedef
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<ll> vll;
typedef vector<vll> vvll;
typedef vector<int> vi;
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;

// macros
#define rep(i,n) for(ll i=0;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)

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); }

using namespace std;

ll find(vll& uf, ll u) {
return uf[u] == u ? u : uf[u] = find(uf, uf[u]);
}

bool uni(vll& uf, ll u, ll v) {
ll pu = find(uf, u), pv = find(uf, v);
if(pu == pv) return false;
uf[pu] = uf[pv] = min(pu, pv);
return true;
}

vll solve(ll n, vpll& E) {
vll uf(n + 1);
vll res(n);
vll adj[n + 1];
for(auto& [u, v] : E) {
adj[min(u,v)].push_back(max(u,v));
}

rep(i, n + 1) uf[i] = i;
ll c = 0;
rrep(u, 1, n) {
res[u-1] = c;
c++;
for(auto& v : adj[u]) {
if(uni(uf, u,v)) --c;
}
}


return res;
}

int main() {
Code By Sumfi

//cout.precision(12);

ll tc = 1;
//cin>>tc;
for (ll i = 1; i <= tc; i++) {
ll n, e;
cin>>n>>e;
vpll E(e);
rep(i,e) cin>>E[i].first>>E[i].second;
for(auto& r : solve(n,E)) cout<<r<<endl;
}
return 0;
}


Author: Song Hayoung
Link: https://songhayoung.github.io/2022/06/26/PS/AtCoder/abc229-e/
Copyright Notice: All articles in this blog are licensed under CC BY-NC-SA 4.0 unless stating additionally.

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