結果

問題 No.1553 Lovely City
ユーザー Ogtsn99
提出日時 2021-06-19 17:44:31
言語 C++17
(gcc 13.3.0 + boost 1.87.0)
結果
AC  
実行時間 745 ms / 2,000 ms
コード長 7,447 bytes
コンパイル時間 2,684 ms
コンパイル使用メモリ 213,324 KB
最終ジャッジ日時 2025-01-22 10:07:21
ジャッジサーバーID
(参考情報)
judge3 / judge4
このコードへのチャレンジ
(要ログイン)
ファイルパターン 結果
sample AC * 2
other AC * 26
権限があれば一括ダウンロードができます

ソースコード

diff #
プレゼンテーションモードにする

#include <bits/stdc++.h>
using namespace std;
#define int long long
#define rep(i, n) for(int (i)=0;(i)<(n);(i)++)
#define rrep(i, n) for(int (i)=((n)-1);(i)>=0;(i)--)
#define itn int
#define miele(v) min_element(v.begin(), v.end())
#define maele(v) max_element(v.begin(), v.end())
#define SUM(v) accumulate(v.begin(), v.end(), 0LL)
#define lb(a, key) lower_bound(a.begin(),a.end(),key)
#define ub(a, key) upper_bound(a.begin(),a.end(),key)
#define COUNT(a, key) count(a.begin(), a.end(), key)
#define BITCOUNT(x) __builtin_popcount(x)
#define pb push_back
#define all(x) (x).begin(),(x).end()
#define F first
#define S second
using P = pair<int, int>;
using WeightedGraph = vector<vector<P>>;
using UnWeightedGraph = vector<vector<int>>;
using Real = long double;
using Point = complex<Real>; //Point and Vector2d is the same!
// p.real() or real(p) -> x, p.imag() or imag(p) -> y
using Vector2d = complex<Real>;
const int MOD = 1000000007;
const long long INF = 1LL << 60;
const double EPS = 1e-15;
const double PI = 3.14159265358979323846;
template<typename T>
int getIndexOfLowerBound(vector<T> &v, T x) {
return lower_bound(v.begin(), v.end(), x) - v.begin();
}
template<typename T>
int getIndexOfUpperBound(vector<T> &v, T x) {
return upper_bound(v.begin(), v.end(), x) - v.begin();
}
template<class T>
inline bool chmin(T &a, T b) {
if (a > b) {
a = b;
return true;
}
return false;
}
template<class T>
inline bool chmax(T &a, T b) {
if (a < b) {
a = b;
return true;
}
return false;
}
#define repi(itr, ds) for (auto itr = ds.begin(); itr != ds.end(); itr++)
istream &operator>>(istream &is, Point &p) {
Real a, b;
is >> a >> b;
p = Point(a, b);
return is;
}
template<typename T, typename U>
istream &operator>>(istream &is, pair<T, U> &p_var) {
is >> p_var.first >> p_var.second;
return is;
}
template<typename T>
istream &operator>>(istream &is, vector<T> &vec) {
for (T &x : vec) is >> x;
return is;
}
template<typename T, typename U>
ostream &operator<<(ostream &os, pair<T, U> &pair_var) {
os << pair_var.first << ' ' << pair_var.second;
return os;
}
template<typename T>
ostream &operator<<(ostream &os, vector<T> &vec) {
for (int i = 0; i < vec.size(); i++)
os << vec[i] << ' ';
return os;
}
template<typename T, typename U>
ostream &operator<<(ostream &os, vector<pair<T, U>> &vec) {
for (int i = 0; i < vec.size(); i++)
os << vec[i] << '\n';
return os;
}
template<typename T>
ostream &operator<<(ostream &os, vector<vector<T>> &df) {
for (auto &vec : df) os << vec;
return os;
}
template<typename T, typename U>
ostream &operator<<(ostream &os, map<T, U> &map_var) {
repi(itr, map_var) {
os << *itr << ' ';
itr++;
itr--;
}
return os;
}
template<typename T>
ostream &operator<<(ostream &os, set<T> &set_var) {
repi(itr, set_var) {
os << *itr << ' ';
itr++;
itr--;
}
return os;
}
void print() { cout << endl; }
template<class Head, class... Tail>
void print(Head &&head, Tail &&... tail) {
cout << head;
if (sizeof...(tail) != 0) cout << " ";
print(forward<Tail>(tail)...);
}
//#https://ei1333.github.io/luzhiled/snippets/graph/strongly-connected-components.htmlorz
template<typename G>
struct StronglyConnectedComponents {
const G &g;
UnWeightedGraph gg, rg;
vector<int> comp, order, used;
StronglyConnectedComponents(G &g) : g(g), gg(g.size()), rg(g.size()), comp(g.size(), -1), used(g.size()) {
for (int i = 0; i < g.size(); i++) {
for (auto e : g[i]) {
gg[i].emplace_back((int) e);
rg[(int) e].emplace_back(i);
}
}
}
int operator[](int k) {
return comp[k];
}
void dfs(int idx) {
if (used[idx]) return;
used[idx] = true;
for (int to : gg[idx]) dfs(to);
order.push_back(idx);
}
void rdfs(int idx, int cnt) {
if (comp[idx] != -1) return;
comp[idx] = cnt;
for (int to : rg[idx]) rdfs(to, cnt);
}
void build(UnWeightedGraph &t) {
for (int i = 0; i < gg.size(); i++) dfs(i);
reverse(begin(order), end(order));
int ptr = 0;
for (int i : order) if (comp[i] == -1) rdfs(i, ptr), ptr++;
t.resize(ptr);
for (int i = 0; i < g.size(); i++) {
for (auto &to : g[i]) {
int x = comp[i], y = comp[to];
if (x == y) continue;
t[x].push_back(y);
}
}
}
};
signed main(void) { cin.tie(0); ios::sync_with_stdio(false);
int n, m; cin>>n>>m;
UnWeightedGraph g(n), bidirectional_g(n);
rep(i, m) {
int u, v; cin>>u>>v;
u--, v--;
g[u].pb(v);
bidirectional_g[u].pb(v);
bidirectional_g[v].pb(u);
}
StronglyConnectedComponents<UnWeightedGraph> scc(bidirectional_g);
UnWeightedGraph t;
scc.build(t);
UnWeightedGraph newG(n);
for (int i = 0; i < n; ++i) {
for (int j = 0; j < g[i].size(); ++j) {
if(scc[g[i][j]] == scc[i]) {
newG[i].pb(g[i][j]);
}
}
}
vector<vector<int>> elementList(t.size());
vector<int> deg(n);
for (int i = 0; i < n; ++i) {
elementList[scc[i]].pb(i);
for (auto to : newG[i]) {
deg[to]++;
}
}
vector<pair<int, int>> ans;
vector<int> used(t.size());
// deg[i] == 0 i
for (int i = 0; i < n; ++i) {
if(!used[scc[i]]) {
used[scc[i]] = true;
queue<int> q;
stack<int> st;
for (int j = 0; j < elementList[scc[i]].size(); ++j) {
if(deg[elementList[scc[i]][j]] == 0) {
st.push(elementList[scc[i]][j]);
q.push(elementList[scc[i]][j]);
}
}
while(!st.empty()) {
int now = st.top(); st.pop();
for (int j = 0; j < newG[now].size(); ++j) {
deg[newG[now][j]]--;
if(deg[newG[now][j]]==0) {
q.push(newG[now][j]);
st.push(newG[now][j]);
}
}
}
if(q.size() == elementList[scc[i]].size()) {
int now = q.front(); q.pop();
while(!q.empty()) {
int ne = q.front(); q.pop();
ans.pb({now, ne});
now = ne;
}
} else {
int now = -1;
int first = -1;
int group = scc[i];
for (int j = 0; j < elementList[group].size(); ++j) {
int e = elementList[group][j];
if(j == 0) {
now = first = e;
} else if(j == elementList[group].size() - 1) {
ans.pb({now, e});
ans.pb({e, first});
} else {
ans.pb({now, e});
now = e;
}
}
}
}
}
print(ans.size());
for (int i = 0; i < ans.size(); ++i) {
print(ans[i].F+1, ans[i].S+1);
}
}
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