/// In The Name Of God
#pragma GCC optimize("Ofast")
#pragma GCC target_("sse,sse2,sse3,sse3,sse4,popcnt,abm,mmx")
#include <bits/stdc++.h>
#define f first
#define s second
#define pb push_back
#define pp pop_back
#define mp make_pair
#define sz(x) (int)x.size()
#define sqr(x) ((x) * 1ll * (x))
#define all(x) x.begin(), x.end()
#define Kazakhstan ios_base :: sync_with_stdio(0), cin.tie(0), cout.tie(0);
#define nl '\n'
#define ioi exit(0);
typedef long long ll;
typedef long double ld;
typedef unsigned long long ull;
const int N = (int)2e5 + 7, inf = (int)1e9 + 7, mod = (int)1e9 + 7;
const ll linf = (ll)1e18 + 7;
const int dx[] = {-1, 0, 1, 0, 1, -1, -1, 1}, dy[] = {0, 1, 0, -1, 1, -1, 1, -1};
using namespace std;
int get__int() {
char x = getchar();
int res = 0;
while (!isdigit(x)) res = res * 10 + x - '0', x = getchar();
while (isdigit(x)) res = res * 10 + x - '0', x = getchar();
return res;
}
int n;
vector <int> g[N];
vector <int> cycle;
int from[N];
bool was[N], bad[N];
void find_cycle(int v = 1, int p = -1) {
was[v] = 1;
from[v] = p;
for (auto to : g[v]) {
if (to == p) continue;
if (was[to] && !sz(cycle)) {
int x = v;
while (1) {
cycle.pb(x);
bad[x] = 1;
if (x == to) break;
x = from[x];
}
}
else if (!was[to]) find_cycle(to, v);
}
}
ll ans;
int mx;
int dp[N];
void dfs(int v, int p = -1) {
priority_queue <int> st;
for (auto to : g[v]) {
if (to == p || bad[to]) continue;
dfs(to, v);
st.push(dp[to]);
dp[v] = max(dp[v], dp[to] + 1);
}
for (int i = 1, cur = 0; i <= min(2, sz(st)); i++, st.pop()) {
cur += st.top() + 1;
mx = max(mx, cur);
}
}
pair <int, int> mxv[N];
void dfs1(int v, int p = - 1) {
map <int, int> cnt;
for (auto to : g[v]) {
if (to == p || bad[to]) continue;
dfs1(to, v);
cnt[dp[to]]++;
}
mxv[v].s = 1;
if (sz(cnt)) {
auto it = --cnt.end();
mxv[v] = *it;
if (it -> f == mx) ans += (ll)it -> s * (it -> s - 1) / 2;
else if (sz(cnt) > 1) {
pair <int, int> l1 = *it;
--it;
pair <int, int> l2 = *it;
if (l1.f + l2.f == mx) ans += (ll)l1.s * l2.s;
}
}
}
int main() {
#ifdef IOI2018
freopen ("in.txt", "r", stdin);
freopen ("C.out", "w", stdout);
#endif
Kazakhstan
cin >> n;
for (int i = 1; i <= n; i++) {
int v, u;
cin >> v >> u;
g[v].pb(u);
g[u].pb(v);
}
find_cycle();
for (auto it : cycle) {
bool ok = 0;
for (auto to : g[it]) {
if (!bad[to]) {
ok = 1;
break;
}
}
if (ok) dfs(it);
mx = max(mx, dp[it] + sz(cycle) / 2);
}
int sz = sz(cycle), add = sz / 2;
for (int i = 0; i < add; i++) {
cycle.pb(cycle[i]);
}
if (sz > 3) {
set <int> st[2];
for (int i = 0; i < sz(cycle); i++) {
if (i >= sz) {
int l = i - sz;
st[l % 2].erase(dp[cycle[l]] - l);
}
if (i >= 2) mx = max(mx, dp[cycle[i]] + i + *st[i % 2].rbegin());
st[i % 2].insert(dp[cycle[i]] - i);
}
}
for (int i = 1; i <= n; i++) {
if (dp[i]) {
if (dp[i] + add == mx) ans += 1 + (sz % 2);
}
else if (dp[i] + add == mx) ans++;
}
for (auto it : cycle) {
bool ok = 0;
for (auto to : g[it]) {
if (!bad[to]) {
ok = 1;
break;
}
}
if (ok) dfs1(it);
}
if (sz > 3) {
map <int, int> s[2];
for (int i = 0; i < sz(cycle); i++) {
if (i >= sz) {
int l = i - sz;
s[l % 2][dp[cycle[l]] - l] -= mxv[cycle[l]].s;
if (s[l % 2][dp[cycle[l]] - l] == 0) s[l % 2].erase(dp[cycle[l]] - l);
}
if (i >= 3) {
if (dp[cycle[i]] + i + s[i % 2].rbegin() -> f == mx) {
ans += (ll)mxv[cycle[i]].s * s[i % 2].rbegin() -> s;
}
}
s[i % 2][dp[cycle[i]] - i] += mxv[cycle[i]].s;
}
}
cout << ans;
ioi
}
Compilation message
shymbulak.cpp:4:0: warning: ignoring #pragma GCC target_ [-Wunknown-pragmas]
#pragma GCC target_("sse,sse2,sse3,sse3,sse4,popcnt,abm,mmx")
^
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
3 ms |
10388 KB |
Output is correct |
| 2 |
Incorrect |
3 ms |
10388 KB |
Output isn't correct |
| 3 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Incorrect |
3 ms |
10388 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Incorrect |
133 ms |
13292 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
