#include <bits/stdc++.h>
#define ll long long
#define pii pair<int,int>
#define pll pair<ll,ll>
#define vi vector<int>
#define vl vector<ll>
#define mp make_pair
#define pb push_back
#define se second
#define fi first
using namespace std;
void __print(int x) {cerr << x;}
void __print(long x) {cerr << x;}
void __print(long long x) {cerr << x;}
void __print(unsigned x) {cerr << x;}
void __print(unsigned long x) {cerr << x;}
void __print(unsigned long long x) {cerr << x;}
void __print(float x) {cerr << x;}
void __print(double x) {cerr << x;}
void __print(long double x) {cerr << x;}
void __print(char x) {cerr << '\'' << x << '\'';}
void __print(const char *x) {cerr << '\"' << x << '\"';}
void __print(const string &x) {cerr << '\"' << x << '\"';}
void __print(bool x) {cerr << (x ? "true" : "false");}
template<typename T, typename V>
void __print(const pair<T, V> &x) {cerr << '{'; __print(x.first); cerr << ','; __print(x.second); cerr << '}';}
template<typename T>
void __print(const T &x) {int f = 0; cerr << '{'; for (auto &i: x) cerr << (f++ ? "," : ""), __print(i); cerr << "}";}
void _print() {cerr << "]\n";}
template <typename T, typename... V>
void _print(T t, V... v) {__print(t); if (sizeof...(v)) cerr << ", "; _print(v...);}
#ifndef ONLINE_JUDGE
#define debug(x...) cerr << "[" << #x << "] = ["; _print(x)
#else
#define debug(x...)
#endif
clock_t startTime;
double getCurrentTime() {
return (double)(clock() - startTime) / CLOCKS_PER_SEC;
}
ll set_on(ll n, ll k){
return (n |= 1 << k);
}
ll set_off(ll n, ll k){
return (n &= ~(1UL << k));
}
bool check_bit(ll n, ll k){
int bit = (n >> k) & 1U;
if(bit == 1)
return true;
return false;
}
int n;
vi G[200100];
int ans = 1e9, sum[200100], depth[200100];
vi segtree, euler, first;
vector<bool> vis;
void dfs2(int at){
vis[at] = true;
first[at] = euler.size();
euler.pb(at);
for(auto next : G[at]){
if(!vis[next]){
dfs2(next);
euler.pb(at);
}
}
}
void build(int node, int l, int r){
if(l == r){
segtree[node] = euler[l];
}
else{
int mid = (l + r) / 2;
build(node * 2, l, mid);
build(node * 2 + 1 ,mid + 1, r);
int left = segtree[node * 2];
int right= segtree[node * 2 + 1];
segtree[node] = (depth[left] < depth[right]) ? left : right;
}
}
void LCA(int root = 0){
vis.assign(n, false);
first.resize(n);
euler.reserve(2 * n);
dfs2(root);
segtree.resize(4 * euler.size());
build(1, 0, euler.size()-1);
}
int query(int node, int l, int r, int L, int R){
if(r < L || l > R) return -1;
if(L <= l && r <= R) return segtree[node];
int mid = (l + r) / 2;
int left = query(node * 2, l, mid, L, R);
int right = query(node * 2 + 1, mid + 1, r, L, R);
if(left == -1) return right;
if(right == -1) return left;
return (depth[left] < depth[right]) ? left : right;
}
int lca(int u, int v){
int left = first[u], right = first[v];
if(left > right)
swap(left, right);
return query(1, 0, euler.size()-1, left, right);
}
void get_depth(int at, int prev, int dep){
depth[at] = dep;
for(auto next : G[at]){
if(next == prev) continue;
get_depth(next, at, dep + 1);
}
}
void dfs(int at, int prev){
sum[at] = 1;
for(auto next : G[at]){
if(next == prev) continue;
dfs(next, at);
sum[at] += sum[next];
}
}
bool comp(int& A, int& B){
if(depth[A] >= depth[B]) return false;
return true;
}
void solve(){
cin>>n;
vector<pii> edge;
for(int i = 1; i < n; i++){
int a, b;
cin>>a>>b;
a--; b--;
G[a].pb(b);
G[b].pb(a);
edge.pb(mp(a,b));
}
LCA();
get_depth(0, -1, 0);
dfs(0, -1);
for(int i = 0; i < edge.size(); i++){
for(int j = i + 1; j < edge.size(); j++){
int a = sum[0];
int b= sum[edge[i].se];
int c = sum[edge[j].se];
if(lca(edge[i].se, edge[j].se) == 0){
a -= c;
a -= b;
}
else if(lca(edge[i].se, edge[j].se) == edge[i].se){
a -= b;
b -= c;
}
else if(lca(edge[i].se, edge[j].se) == edge[j].se){
a -= c;
c -= b;
}
int maks = max(a, max(b,c));
int mins = min(a, min(b,c));
ans = min(ans, maks - mins);
}
}
cout<<ans<<endl;
}
int main(){
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
cout.precision(10);
cout<<fixed;
startTime = clock();
int t=1;
// cin>>t;
while(t--)
solve();
return 0;
}
Compilation message
papricice.cpp: In function 'void solve()':
papricice.cpp:142:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
142 | for(int i = 0; i < edge.size(); i++){
| ~~^~~~~~~~~~~~~
papricice.cpp:143:24: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
143 | for(int j = i + 1; j < edge.size(); j++){
| ~~^~~~~~~~~~~~~
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
6 ms |
4948 KB |
Output is correct |
| 2 |
Incorrect |
7 ms |
4948 KB |
Output isn't correct |
| 3 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
6 ms |
4948 KB |
Output is correct |
| 2 |
Incorrect |
7 ms |
4948 KB |
Output isn't correct |
| 3 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
6 ms |
4948 KB |
Output is correct |
| 2 |
Incorrect |
7 ms |
4948 KB |
Output isn't correct |
| 3 |
Halted |
0 ms |
0 KB |
- |
