제출 #91067

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
91067		daniel_02	관광지 (IZhO14_shymbulak)	C++17	0 / 100	235 ms	21688 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;
		}
	}
}
int deep(int v, int p, int &cnt, int x, int c = 1)
{
	int mx = c;
	if (c == x)
	{
		cnt++;
	}
	for (int i = 0; i < g[v].size(); i++)
	{
		int to = g[v][i];
		if (to == p)continue;
		mx = max(mx, deep(to, v, cnt, x, c + 1));
	}
	return mx;
}
void dfs1(int v, int p, int id)
{
	us[v] = 1;
	cycn++;
	us[v] = 1;
	int mx = 0, trash = 0;
	for (int i = 0; i < g[v].size(); i++)
	{
		int to = g[v][i];
		if (!is_b[{v, to}])continue;
		mx = max(mx, deep(to, v, trash, 0));
	}
	int cnt = 0;
	bool fl = 0;
	for (int i = 0; i < g[v].size(); i++)
	{
		int to = g[v][i];
		if (!is_b[{v, to}])continue;
		deep(to, v, cnt, mx);
		fl = 1;
	}
	if (!fl)cnt = 1;
	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]);
		if (st2.size())
		{
			len = (*st2.begin()) - id + c[id];
			mx = max(mx, len);
			cnt[len] += (mp2[len + id - c[id]] * 1LL * qt[id]);
		}
	}
	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);
		st2.insert(c[id - prev] + cycn + id - prev);
		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]);
		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
*/

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 'int deep(int, int, int&, int, int)':
shymbulak.cpp:56:20: 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:70:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < g[v].size(); i++)
                  ~~^~~~~~~~~~~~~
shymbulak.cpp:78:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < g[v].size(); i++)
                  ~~^~~~~~~~~~~~~
shymbulak.cpp:88:20: 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:126:20: 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:133:6: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
 main()
      ^
shymbulak.cpp: In function 'int main()':
shymbulak.cpp:142:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%d", &a, &b);
   ~~~~~^~~~~~~~~~~~~~~~

• Subtask 1: 0 / 30
• Subtask 2: 0 / 20
• Subtask 3: 0 / 50