제출 #91181

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
91181		daniel_02	관광지 (IZhO14_shymbulak)	C++17	100 / 100	1143 ms	41300 KiB

shymbulak

#include <bits/stdc++.h>

#define fr first
#define pb push_back
#define sc second
#define ll long long

using namespace std;

const int N = 2e5 + 7;
const int inf = 1e9 + 7;

vector<int>g[N];
int c[N];
set<int, greater<int>>st1;
set<int, greater<int>>st2;
map<int, ll>mp1;
map<int, ll>mp2;
map<ll, ll>cnt;
int qt[N], tin[N], cn, fup[N];
ll mx = -1;
map<pair<int, int>, bool>is_b;
bool us[N];
int ver;
int cycn;
void dfs(int v, int p)
{	
	tin[v] = fup[v] = ++cn;
	us[v] = 1;
	for (int i = 0; i < g[v].size(); i++)
	{
		int to = g[v][i];
		if (to == p)continue;
		if (us[to])
		{
			fup[v] = min(fup[v], tin[to]);
		}
		else
		{
			dfs(to, v);
			fup[v] = min(fup[v], fup[to]);
			if (fup[to] > tin[v])
				is_b[{v, to}] = 1, is_b[{to, v}] = 1;
			else
				ver = to;
		}
	}
}
pair<int, int> deep(int v, int p)
{
	ll mxx = -1, mx1 = -1;
	ll eq = 1, eq1 = 1;
	ll col = 0, sm = 0;
	for (int i = 0; i < g[v].size(); i++)
	{
		int to = g[v][i];
		if (to == p || !is_b[{v, to}])continue;
		pair<ll, ll> q = deep(to, v);
		if (mxx < q.fr)
		{
			eq1 = eq;
			mx1 = mxx;
			mxx = q.fr;
			eq = q.sc;
			sm = q.sc;
		}
		else
		{
			if (q.fr == mxx){
				eq += q.sc;
				col += (q.sc * sm);
				sm += q.sc;
			}
			if (q.fr == mx1)
				eq1 += q.sc;
			if (q.fr > mx1)
				eq1 = q.sc;
			mx1 = max(mx1, q.fr * 1LL);
		}
		//cout << v << " " << mx1 << " <-> " << mxx << " " << eq << " " << eq1 << " " << col << endl;
	}
	mxx++; mx1++;
	if (mxx != mx1)
	{
		col = eq * eq1;
	}
	//cout << v << " " << mxx << " " << mx1 << " " << eq << " " << eq1 << " " << col << endl;
	mx = max(mxx + mx1, mx);
	cnt[mxx + mx1] += col;
	//cout << v << " " << mxx + mx1 << " " << cnt[mxx + mx1] << " " << mx << endl; 
	return {mxx, eq};
}
void dfs1(int v, int p, int id)
{
	us[v] = 1;
	cycn++;
	us[v] = 1;
	int mx = 0;
	int cnt = 0;
	pair<int, int>q = deep(v, p);
	mx = q.fr, cnt = q.sc;
	c[id] = mx;
	qt[id] = cnt;
	for (int i = 0; i < g[v].size(); i++)
	{
		int to = g[v][i];
		if (us[to] || is_b[{v, to}])continue;
		dfs1(to, v, id + 1);
	}
}
void dfs2(int v, int p, int id)
{
	us[v] = 1;
	if (id != 0)
	{
		ll len = (*st1.begin()) + id + c[id];
		mx = max(mx, len);
		cnt[len] += (mp1[len - id - c[id]] * 1LL * qt[id]);
		//cout << v << " " << id << " " << len << " " << mp1[len - id - c[id]] * 1LL * qt[id] << endl;
		if (st2.size())
		{
			len = (*st2.begin()) - id + c[id];
			mx = max(mx, len);
			cnt[len] += (mp2[len + id - c[id]] * 1LL * qt[id]);
		//cout << v << " " << id << " " << len << " " << mp2[len + id - c[id]] * 1LL * qt[id] << endl;
		}
		//cout << endl;
	}
	st1.insert(c[id] - id);
	mp1[c[id] - id] += qt[id];
	int prev = cycn / 2;
	if (id >= prev)
	{
		mp1[c[id - prev] - id + prev] -= qt[id - prev];
		if (mp1[c[id - prev] - id + prev] == 0)
			st1.erase(c[id - prev] - id + prev);
		if (cycn % 2){
			st2.insert(c[id - prev] + cycn + id - prev);
			//cout << " <<<- " << c[id - prev] + cycn + id - prev << " " << qt[id - prev] << endl;
			mp2[c[id - prev] + cycn + id - prev] += qt[id - prev];
		}
	}
	if (cycn % 2 == 0 && id >= prev - 1)
	{
		st2.insert(cycn + (id - prev + 1) + c[id - prev + 1]);
		//cout << " ->>> " << cycn + (id - prev + 1) + c[id - prev + 1] << " " << qt[id - prev + 1] << endl;
		mp2[cycn + (id - prev + 1) + c[id - prev + 1]] += qt[id - prev + 1];
	}
	for (int i = 0; i < g[v].size(); i++)
	{
		int to = g[v][i];
		if (is_b[{v, to}] || us[to])continue;
		dfs2(to, v, id + 1);
	}
}
main()
{
	int n;
	
	cin >> n;
	
	for (int i = 1; i <= n; i++)
	{
		int a, b;
		scanf("%d%d", &a, &b);
		g[a].pb(b);
		g[b].pb(a);
	}
	
	dfs(1, 0);
	memset(us, 0, sizeof(us));
	
	dfs1(ver, 0, 0);
	memset(us, 0, sizeof(us));
	dfs2(ver, 0, 0);
	//cout << mx << endl;
	cout << cnt[mx] << endl;
}
/*
 * Find Bridges
 * Assign c[i]s (length of subtree) and q[i] number of them and cyc -> length of cycle 
 * Dance
*/
/*
12
5 11
5 4
4 3
3 6
11 7
11 10
4 9
11 12
4 1
5 8
11 2
6 2
*/

컴파일 시 표준 에러 (stderr) 메시지

shymbulak.cpp: In function 'void dfs(int, int)':
shymbulak.cpp:30:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < g[v].size(); i++)
                  ~~^~~~~~~~~~~~~
shymbulak.cpp: In function 'std::pair<int, int> deep(int, int)':
shymbulak.cpp:54:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < g[v].size(); i++)
                  ~~^~~~~~~~~~~~~
shymbulak.cpp: In function 'void dfs1(int, int, int)':
shymbulak.cpp:104:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < g[v].size(); i++)
                  ~~^~~~~~~~~~~~~
shymbulak.cpp: In function 'void dfs2(int, int, int)':
shymbulak.cpp:149:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < g[v].size(); i++)
                  ~~^~~~~~~~~~~~~
shymbulak.cpp: At global scope:
shymbulak.cpp:156:6: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
 main()
      ^
shymbulak.cpp: In function 'int main()':
shymbulak.cpp:165:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%d", &a, &b);
   ~~~~~^~~~~~~~~~~~~~~~

• Subtask 1: 30 / 30
• Subtask 2: 20 / 20
• Subtask 3: 50 / 50