//#pragma GCC target ("avx2")
//#pragma GCC optimization ("Ofast")
//#pragma GCC optimization ("unroll-loops")
//#pragma comment(linker,"/stack:200000000")
//#pragma GCC optimize("Ofast")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
//order_of_key(k): Number of items strictly smaller than k .
//find_by_order(k): K-th element in a set (counting from zero).
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#define full(x,n) x,x+n+1
#define full(x) x.begin(),x.end()
#define finish return 0
#define putb push_back
#define f first
#define s second
//logx(a^n)=loga(a^n)/logx(a)
//logx(a*b)=logx(a)+logx(b)
//logx(y)=log(y)/log(x)
//logb(n)=loga(n)/loga(b)
#define ordered_set tree<ll,null_type,less<ll>,rb_tree_tag,tree_order_statistics_node_update>
#define putf push_front
#define gainb pop_back
//(a+b)^n=sum of C(n,i)*a^i*b^(n-i) 0<=i<=n
//(a-b)^n=sum of C(n,i)*a^i*b^(n-i) for even i-for odd i
#define gainf pop_front
#define len(x) (int)x.size()
// 1/b%mod=b^(m-2)%mod
// (a>>x)&1==0
// a^b=(a+b)-2(a&b)
typedef double db;
typedef long long ll;
//sum of squares n*(n+1)*(2n+1)/6
//sum of cubes [n*(n+1)/2]^2
//sum of squares for odds n*(4*n*n-1)/3
//sum of cubes for odds n*n*(2*n*n-1)
const int ary=1e6+5;
const ll mod=1e9+7;
const ll inf=1e18;
using namespace std;
using namespace __gnu_pbds;
int n,p[ary],c[ary],k[ary],e[ary],d[ary],ans,mx;
vector<int> g[ary],q,r,t;
void dfs(int v=1){
c[v]=1;
for(int i=0;i<len(g[v]);i++){
int to=g[v][i];
if(to==p[v]){
continue;
}
if(c[to]==2){
continue;
}
if(!c[to]){
p[to]=v;
dfs(to);
continue;
}
int u=v;
while(1){
q.push_back(u);
k[u]=len(q);
if(u==to){
break;
}
u=p[u];
}
}
c[v]=2;
}
void go(int v,int pr=0){
for(int i=0;i<len(r);i++){
int x=min(abs(k[e[v]]-k[e[r[i]]]),len(q)-abs(k[e[v]]-k[e[r[i]]]));
if(x+d[v]+d[r[i]]>mx){
ans=0;
mx=x+d[v]+d[r[i]];
}
if(x+d[v]+d[r[i]]==mx){
ans++;
ans+=(abs(k[e[v]]-k[e[r[i]]])==len(q)-abs(k[e[v]]-k[e[r[i]]]));
}
}
t.push_back(v);
for(int i=0;i<len(g[v]);i++){
int to=g[v][i];
if(to==pr||k[to]){
continue;
}
d[to]=d[v]+1;
e[to]=e[v];
go(to,v);
}
}
void run(int v,int pr=0,int cnt=0){
if(d[v]>mx){
ans=0;
mx=d[v];
}
if(d[v]==mx){
ans++;
}
for(int i=0;i<len(g[v]);i++){
int to=g[v][i];
if(to==pr||cnt+(k[to]>0)==2){
continue;
}
d[to]=d[v]+1;
run(to,v,cnt+(k[to]>0));
}
}
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0);cout.tie(0);
cin>>n;
for(int i=1;i<=n;i++){
int a,b;
cin>>a>>b;
g[a].push_back(b);
g[b].push_back(a);
}
dfs();
for(int i=0;i<len(q);i++){
e[q[i]]=q[i];
go(q[i]);
while(len(t)){
r.push_back(t.back());
t.pop_back();
}
}
/*for(int i=1;i<=n;i++){
if(k[i]){
continue;
}
d[i]=0;
run(i);
}*/
cout<<ans;
}
Compilation message
shymbulak.cpp:15: warning: "full" redefined
15 | #define full(x) x.begin(),x.end()
|
shymbulak.cpp:14: note: this is the location of the previous definition
14 | #define full(x,n) x,x+n+1
|
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
11 ms |
23756 KB |
Output is correct |
| 2 |
Incorrect |
10 ms |
23720 KB |
Output isn't correct |
| 3 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
11 ms |
23884 KB |
Output is correct |
| 2 |
Incorrect |
13 ms |
23888 KB |
Output isn't correct |
| 3 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Incorrect |
50 ms |
29348 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
