#define _CRT_SECURE_NO_WARNINGS
#include <bits/stdc++.h>
//#include "temp.cpp"
#include <cstdio>
using namespace std;
#pragma GCC optimize("Ofast")
#ifndef ONLINE_JUDGE
#define dbg(x) cerr << #x <<" "; print(x); cerr << endl;
#else
#define dbg(x)
#endif
#define sz(x) (int((x).size()))
#define len(x) (int)x.length()
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define clr(x) (x).clear()
#define uniq(x) x.resize(unique(all(x)) - x.begin());
#define pb push_back
#define popf pop_front
#define popb pop_back
void print(long long t) {cerr << t;}
void print(int t) {cerr << t;}
void print(string t) {cerr << t;}
void print(char t) {cerr << t;}
void print(double t) {cerr << t;}
void print(long double t) {cerr << t;}
void print(unsigned long long t) {cerr << t;}
template <class T> void print(set <T> v);
template <class T> void print(vector <T> v);
template <class T> void print(multiset <T> v);
template <class T, class V> void print(map <T, V> v);
template <class T, class V> void print(pair <T, V> p);
template <class T, class V> void print(T v[],V n) {cerr << "["; for(int i = 0; i < n; i++) {print(v[i]); cerr << " "; } cerr << "]";}
template <class T, class V> void print(pair <T, V> p) {cerr << "{"; print(p.first); cerr << ","; print(p.second); cerr << "}";}
template <class T> void print(vector <T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T> void print(set <T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T> void print(multiset <T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T, class V> void print(map <T, V> v) {cerr << "[ "; for (auto i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T, class V> void print(unordered_map<T, V> v) {cerr << "[ "; for (auto i : v) {print(i); cerr << " ";} cerr << "]";}
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
#define nl '\n'
// for grid problems
long long dx[8] = {-1,0,1,0,1,-1,1,-1};
long long dy[8] = {0,1,0,-1,1,1,-1,-1};
// lowest / (1 << 17) >= 1e5 / (1 << 18) >= 2e5 / (1 << 21) >= 1e6
void fastIO() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr); cout.tie(nullptr);
}
// file in/out
void setIO(string str = "") {
fastIO();
if (str != "" && str != "input") {
freopen((str + ".in").c_str(), "r", stdin);
freopen((str + ".out").c_str(), "w", stdout);
}
if(str == "input") {
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
}
}
// Indexed Set
template <class T> using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
const long long N = 2e5 + 10;
vector<long long> adj[N], cycle;
long long n, p[N], maxDist, depth[N];
pair<long long, long long> answNode[N];
bool used[N];
long long answ;
bool flag = false;
void getCycle(long long node, long long parent) {
used[node] = true;
p[node] = parent;
for(auto i: adj[node]) {
if(i == parent) continue;
if(used[i]) {
// we get cycle
long long curr = node;
while(curr != i) {
// dbg(curr)
cycle.push_back(curr);
curr = p[curr];
} cycle.push_back(i);
flag = true;
// dbg(cycle)
return;
} else {
getCycle(i, node);
}
if(flag) {
return;
}
}
}
pair<long long, long long> getFurthest(long long node) {
memset(used, false, sizeof(used));
queue<pair<long long, long long>> q;
q.push({node, 0});
used[node] = true;
pair<long long, long long> answ = {node, 0};
while(!q.empty()) {
auto u = q.front();
q.pop();
for(auto i: adj[u.first]) {
if(used[i]) continue;
used[i] = true;
q.push({i, u.second + 1});
if(u.second + 1 > answ.second) {
answ = {i, u.second + 1};
}
}
}
return answ;
}
// dp
pair<long long, long long> dfs(long long node, long long parent) {
vector<pair<long long, long long>> answers;
for(auto i: adj[node]) {
if(used[i] || i == parent) continue;
depth[i] = depth[node] + 1;
answers.push_back(dfs(i, node));
}
if(sz(answers) >= 2) {
sort(all(answers));
long long size = sz(answers);
if(answers[size - 1].first == answers[size - 2].first) {
long long dist = 2 * (answers[size - 1].first - depth[node]);
long long ansi = 0, all = 0;
size--;
// dbg(answers)
while(size >= 0 && answers[size].first == answers.back().first) {
ansi += all * answers[size].second;
all += answers[size--].second;
}
answers[sz(answers) - 1].second = all;
if(dist != maxDist) {
answNode[node] = {answers.back()};
return {answers.back()};
}
answ += ansi;
} else {
long long dist = answers[size - 1].first + answers[size - 2].first - 2 * depth[node];
if(dist != maxDist) {
answNode[node] = {answers.back()};
return {answers.back()};
}
long long l = answers.back().second, r = 0, it = size - 2;
size -= 2;
while(size >= 0 && answers[size].first == answers[it].first) {
r += answers[size--].second;
}
answ += l * r;
}
}
if(answers.empty()) {
answNode[node] = {depth[node], 1};
return {depth[node], 1};
} else {
answNode[node] = {answers.back()};
return {answers.back()};
}
}
void solve_() {
cin >> n;
for(int i = 1; i <= n; i++) {
long long a, b; cin >> a >> b;
adj[a].push_back(b);
adj[b].push_back(a);
}
// we get the path which contain cycle
getCycle(1, 0);
// we should calc the max distance
maxDist = getFurthest(getFurthest(1).first).second;
dbg(cycle)
// get cycle used
memset(used, false, sizeof(used));
for(auto i: cycle) {
used[i] = true;
}
for(auto i: cycle) {
dfs(i, 0);
}
dbg(answ)
for(int i = 0; i < sz(cycle); i++) {
for(int j = i + 1; j < sz(cycle); j++) {
long long minDist = min((long long)(j - i), (long long)(i + sz(cycle) - j));
long long A = cycle[i], B = cycle[j];
if(answNode[A].first + answNode[B].first + minDist == maxDist) {
if(sz(cycle) % 2 == 0 && minDist == sz(cycle) / 2) {
answ += 2 * (answNode[A].second * answNode[B].second);
} else {
answ += (answNode[A].second * answNode[B].second);
}
}
}
}
printf("%lld\n", answ);
}
int main() {
setIO();
auto solve = [&](int test_case)-> void {
while(test_case--) {
solve_();
}
};
int test_cases = 1;
solve(test_cases);
return 0;
}
Compilation message
shymbulak.cpp: In function 'void setIO(std::string)':
shymbulak.cpp:65:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
65 | freopen((str + ".in").c_str(), "r", stdin);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
shymbulak.cpp:66:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
66 | freopen((str + ".out").c_str(), "w", stdout);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
shymbulak.cpp:70:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
70 | freopen("input.txt", "r", stdin);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
shymbulak.cpp:71:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
71 | freopen("output.txt", "w", stdout);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
3 ms |
5204 KB |
Output is correct |
| 2 |
Correct |
4 ms |
5204 KB |
Output is correct |
| 3 |
Correct |
4 ms |
5204 KB |
Output is correct |
| 4 |
Correct |
4 ms |
5204 KB |
Output is correct |
| 5 |
Correct |
3 ms |
5204 KB |
Output is correct |
| 6 |
Correct |
2 ms |
5204 KB |
Output is correct |
| 7 |
Correct |
3 ms |
5188 KB |
Output is correct |
| 8 |
Correct |
3 ms |
5204 KB |
Output is correct |
| 9 |
Correct |
2 ms |
5204 KB |
Output is correct |
| 10 |
Correct |
3 ms |
5204 KB |
Output is correct |
| 11 |
Correct |
3 ms |
5204 KB |
Output is correct |
| 12 |
Correct |
3 ms |
5204 KB |
Output is correct |
| 13 |
Correct |
3 ms |
5204 KB |
Output is correct |
| 14 |
Correct |
3 ms |
5204 KB |
Output is correct |
| 15 |
Incorrect |
4 ms |
5288 KB |
Output isn't correct |
| 16 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
7 ms |
5332 KB |
Output is correct |
| 2 |
Correct |
3 ms |
5332 KB |
Output is correct |
| 3 |
Incorrect |
5 ms |
5332 KB |
Output isn't correct |
| 4 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
78 ms |
12328 KB |
Output is correct |
| 2 |
Correct |
58 ms |
12636 KB |
Output is correct |
| 3 |
Execution timed out |
1593 ms |
17492 KB |
Time limit exceeded |
| 4 |
Halted |
0 ms |
0 KB |
- |
