# include <bits/stdc++.h>
using namespace std;
const int N = 2e5 + 2;
int n, m, used[N], ar[N];
vector <int> g[N], vr;
pair <int, long long> ans, mx[N];
int b[N * 4], val[N * 4];
pair <int, int> t[N * 4];
void cycle(int v, int pr = 0){
used[v] = 1;
vr.push_back(v);
for(int to : g[v]){
if(to == pr)
continue;
if(used[to]){
for(int j = (int)vr.size() - 1; j >= 0; j --){
if(vr[j] == to)
break;
ar[++ m] = vr[j];
}
} else {
cycle(to, v);
}
}
vr.pop_back();
}
void mrg(pair <int, long long> &a, pair <int, long long> b){
b.first ++;
if(b.first > a.first)
a = b;
else if(b.first == a.first)
a.second += b.second;
}
void dfs(int v){
used[v] = 1;
vector < pair <int, long long> > vec;
mx[v] = {0, 1};
for(int to : g[v]){
if(used[to])
continue;
dfs(to);
mrg(mx[v], mx[to]);
mx[to].first ++;
vec.push_back(mx[to]);
mx[to].first --;
}
if(mx[v].first > ans.first){
ans = mx[v];
} else if(mx[v].first == ans.first) {
ans.second += mx[v].second;
}
if((int)vec.size() < 2)
return ;
sort(vec.rbegin(), vec.rend());
while((int)vec.size() > 2 && vec.back().first < vec[1].first)
vec.pop_back();
int ret = vec[0].first + vec[1].first, sz = (int)vec.size();
long long cnt = 0;
if(vec[0].first == vec[1].first){
int sum = 0;
for(int i = 0; i < vec.size(); i ++)
sum += vec[i].second;
for(int i = 0; i < vec.size(); i ++){
cnt += (sum - vec[i].second) * 1ll * vec[i].second;
}
} else {
for(int i = 1; i < vec.size(); i ++)
cnt += vec[i].second;
}
if(ret > ans.first){
ans = {ret, cnt};
} else if(ret == ans.first){
ans.second += cnt;
}
}
pair <int, int> combine(pair <int, int> a, pair <int, int> b){
if(b > a)
swap(a, b);
if(b.first == a.first)
a.second += b.second;
return a;
}
void build(int v = 1, int tl = 1, int tr = m){
if(tl == tr){
t[v] = {mx[ar[tl]].first + min(tl - 1, m - tl + 1), mx[ar[tl]].second};
} else {
int tm = (tl + tr) >> 1;
build(v << 1, tl, tm);
build((v << 1) | 1, tm + 1, tr);
t[v] = combine(t[v << 1], t[(v << 1) | 1]);
}
}
void push(int v, int tl, int tr){
if(b[v]){
t[v].first += val[v];
if(tl != tr){
val[v << 1] += val[v];
val[(v << 1) | 1] += val[v];
b[v << 1] = 1;
b[(v << 1) | 1] = 1;
}
}
b[v] = 0;
val[v] = 0;
}
void update(int l, int r, int x, int v = 1, int tl = 1, int tr = m){
push(v, tl, tr);
if(l > tr || tl > r)
return ;
if(l <= tl && tr <= r){
b[v] = 1;
val[v] += x;
push(v, tl, tr);
return ;
}
int tm = (tl + tr) >> 1;
update(l, r, x, v << 1, tl, tm);
update(l, r, x, (v << 1) | 1, tm + 1, tr);
t[v] = combine(t[v << 1], t[(v << 1) | 1]);
}
pair <int, int> get(int l, int r, int v = 1, int tl = 1, int tr = m){
push(v, tl, tr);
if(l > tr || tl > r)
return {0, 0};
if(l <= tl && tr <= r)
return t[v];
int tm = (tl + tr) >> 1;
return combine(get(l, r, v << 1, tl, tm),
get(l, r, (v << 1) | 1, tm + 1, tr));
}
int main(){
scanf("%d", &n);
for(int i = 1; i <= n; i ++){
int u, v;
scanf("%d %d", &u, &v);
g[u].push_back(v);
g[v].push_back(u);
}
ans = {-1, 0};
cycle(1);
memset(used, 0, sizeof(used));
for(int i = 1; i <= m; i ++)
used[ar[i]] = 1;
for(int i = 1; i <= m; i ++){
dfs(ar[i]);
}
build();
for(int i = 1; i <= m; i ++){
pair <int, long long> ret;
if(i > 1 && i < m){
ret = combine(get(1, i - 1), get(i + 1, m));
} else if(i > 1)
ret = get(1, i - 1);
else
ret = get(i + 1, m);
if(m % 2 == 0){
pair <int, int> p;
if(i + (m / 2) <= m){
p = get(i + (m / 2), i + (m / 2));
} else {
p = get(i - (m / 2), i - (m / 2));
}
if(p.first == ret.first)
ret.second += p.second;
}
ret.first += mx[ar[i]].first;
ret.second = ret.second * mx[ar[i]].second;
if(ret.first > ans.first)
ans = ret;
else if(ret.first == ans.first)
ans.second += ret.second;
int l = i - ((m + 1) / 2 - 1), r = i + (m + 1) / 2;
if(l < 1){
update(1, i, 1);
update(m + l, m, 1);
} else {
update(l, i, 1);
}
if(r > m){
update(i + 1, m, -1);
update(1, r - m, -1);
} else {
update(i + 1, r, -1);
}
}
cout << ans.second / 2 << endl;
}
Compilation message
shymbulak.cpp: In function 'void dfs(int)':
shymbulak.cpp:67:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
for(int i = 0; i < vec.size(); i ++)
~~^~~~~~~~~~~~
shymbulak.cpp:69:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
for(int i = 0; i < vec.size(); i ++){
~~^~~~~~~~~~~~
shymbulak.cpp:73:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
for(int i = 1; i < vec.size(); i ++)
~~^~~~~~~~~~~~
shymbulak.cpp:63:46: warning: unused variable 'sz' [-Wunused-variable]
int ret = vec[0].first + vec[1].first, sz = (int)vec.size();
^~
shymbulak.cpp: In function 'int main()':
shymbulak.cpp:144:12: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
scanf("%d", &n);
~~~~~^~~~~~~~~~
shymbulak.cpp:148:18: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
scanf("%d %d", &u, &v);
~~~~~^~~~~~~~~~~~~~~~~
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
6 ms |
5880 KB |
Output is correct |
| 2 |
Incorrect |
6 ms |
5888 KB |
Output isn't correct |
| 3 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
7 ms |
6100 KB |
Output is correct |
| 2 |
Incorrect |
6 ms |
6124 KB |
Output isn't correct |
| 3 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Incorrect |
59 ms |
11524 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
