#include <bits/stdc++.h>
using namespace std;
#define int ll
typedef long long ll;
typedef long double ld;
typedef pair<int, int> pi;
typedef pair<ll, ll> pl;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef vector<double> vd;
typedef vector<bool> vb;
typedef vector<char> vc;
typedef vector<string> vs;
typedef vector<pi> vp;
typedef vector<pl> vpl;
const int maxn = 5010;
vi e[maxn], cyc(maxn), vis(maxn);
stack<int> st;
bool ciklus = 0;
int len;
void stek(int x){
ciklus = 1;
while(!st.empty()){
cyc[st.top()] = 1;
++len;
if (st.top() == x) break;
st.pop();
}
}
void cycle(int x, int start){
vis[x] = 1;
st.push(x);
for (int y : e[x]){
if (start == y) continue;
if (vis[y]){
stek(y);
break;
}
cycle(y, x);
if (ciklus) break;
}
if (ciklus) return;
st.pop();
}
vi a(maxn, -1), s(maxn);
int poc;
void calc(int x, int st, int d = 0){
if (d > a[poc]){
a[poc] = d;
s[poc] = 1;
} else if (d == a[poc]){
s[poc]++;
}
for (int i : e[x])
if (i != st && !cyc[i])
calc(i, x, d+1);
}
int sol, cnt;
void update(int res, int cc){
if (res == sol)
cnt += cc;
if (res > sol){
sol = res;
cnt = cc;
}
}
void solve(int x, int st, int d = 0){
if (x != st){
int res = d + a[poc] + a[x], cc = s[poc] * s[x];
update(res, cc);
}
for (int i : e[x])
if (i != st && cyc[i] && 2 * (d+1) <= len)
solve(i, x, d+1);
}
int d, cc;
void unutra(int x, int st, int dist = 1){
if (dist == d) ++cc;
if (dist > d){
d = dist;
cc = 1;
}
for (int y : e[x]){
if (y != st)
unutra(y, x, dist+1);
}
}
signed main()
{
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
cout.tie(nullptr);
cerr.tie(nullptr);
int n;
cin >> n;
for (int i = 1; i <= n; ++i){
int u, v;
cin >> u >> v;
e[u].push_back(v);
e[v].push_back(u);
}
cycle(1, 1);
for (int i = 1; i <= n; ++i){
if (!cyc[i]) continue;
poc = i;
calc(i, i);
}
for (int i = 1; i <= n; ++i){
if (cyc[i]){
poc = i;
solve(i,i);
}
}
int test = 0;
for (int i = 1; i <= n; ++i){
if (!cyc[i]) continue;
vp t;
for (int j : e[i]){
if (cyc[j]) continue;
d = 0; cc = 0;
unutra(j, i);
t.push_back({d, cc});
}
sort(t.rbegin(), t.rend());
if (t.empty()) continue;
int sz = t.size();
if (sz == 1){
update(t[0].first, t[0].second*2);
continue;
}
int br = 0, u = t[1].second;
for (int j = 2; j < sz; ++j){
if (t[j].first != t[1].first) break;
++br;
u += t[j].second;
}
if (t[0].first == t[1].first){
int g = 0;
u += t[0].second;
for (int j = 0; j < sz; ++j){
if (t[j].first != t[0].first) break;
g += (u - t[j].second) * t[j].second;
}
int ta = sol, tb= cnt;
update(t[0].first*2, g);
if (sol != ta || cnt != tb)
test = 1;
continue;
}
int ta = sol, tb = cnt;
update(t[0].first + t[1].first, u * t[0].second*2);
if (ta != sol || tb != cnt)
test=2;
}
if (test==2) throw SIGSEGV;
cout << cnt/2 << '\n';
}
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
1 ms |
620 KB |
Output is correct |
2 |
Correct |
1 ms |
620 KB |
Output is correct |
3 |
Correct |
1 ms |
620 KB |
Output is correct |
4 |
Correct |
1 ms |
620 KB |
Output is correct |
5 |
Correct |
1 ms |
620 KB |
Output is correct |
6 |
Correct |
1 ms |
620 KB |
Output is correct |
7 |
Correct |
1 ms |
620 KB |
Output is correct |
8 |
Correct |
1 ms |
620 KB |
Output is correct |
9 |
Correct |
1 ms |
620 KB |
Output is correct |
10 |
Runtime error |
3 ms |
1260 KB |
Execution killed with signal 6 (could be triggered by violating memory limits) |
11 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
12 ms |
620 KB |
Output is correct |
2 |
Correct |
1 ms |
620 KB |
Output is correct |
3 |
Correct |
5 ms |
620 KB |
Output is correct |
4 |
Correct |
1 ms |
620 KB |
Output is correct |
5 |
Correct |
2 ms |
748 KB |
Output is correct |
6 |
Correct |
2 ms |
1004 KB |
Output is correct |
7 |
Runtime error |
5 ms |
1644 KB |
Execution killed with signal 6 (could be triggered by violating memory limits) |
8 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Runtime error |
2 ms |
1152 KB |
Execution killed with signal 11 (could be triggered by violating memory limits) |
2 |
Halted |
0 ms |
0 KB |
- |