//#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;
#define int long long
//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,m,c[ary],p[ary],e[ary],d[ary],dm[ary],k[ary],md[4*ary],diam,ans,q[ary];
vector<int> g[ary];
vector< pair<int,int> > w;
pair<int,int> r[ary];
pair<int,int> t[4*ary];
bool dfs(int v=1,int pr=0){
c[v]=1;
for(int i=0;i<len(g[v]);i++){
int to=g[v][i];
if(to==pr){
continue;
}
if(c[to]==0){
p[to]=v;
if(dfs(to,v)){
return 1;
}
}
else if(c[to]==1){
int u=v;
while(1){
m++;
q[m]=u;
k[u]=m;
if(u==to){
break;
}
u=p[u];
}
return 1;
}
}
c[v]=2;
return 0;
}
void go(int v,int pr=0){
dm[v]=d[v]=d[pr]+1;
e[v]=1;
for(int i=0;i<len(g[v]);i++){
int to=g[v][i];
if(to==pr||k[to]){
continue;
}
go(to,v);
if(dm[v]<dm[to]){
e[v]=0;
dm[v]=dm[to];
}
if(dm[v]==dm[to]){
e[v]+=e[to];
}
}
}
void push(int v,bool ok){
if(md[v]!=0){
t[v].f+=md[v];
if(ok){
md[v*2]+=md[v];
md[v*2+1]+=md[v];
}
md[v]=0;
}
}
void build(int v=1,int tl=1,int tr=m){
if(tl==tr){
t[v]={dm[q[tl]]+min(tl-1,m-(tl-1)),e[q[tl]]};
return;
}
int tm=(tl+tr)/2;
build(v*2,tl,tm);
build(v*2+1,tm+1,tr);
if(t[v*2].f<t[v*2+1].f){
t[v]=t[v*2+1];
}
else if(t[v*2].f>t[v*2+1].f){
t[v]=t[v*2];
}
else{
t[v]={t[v*2].f,t[v*2].s+t[v*2+1].s};
}
}
void upd(int l,int r,int x,int v=1,int tl=1,int tr=m){
push(v,(tl<tr));
if(tr<l||tl>r||l>r){
return;
}
if(l<=tl&&tr<=r){
md[v]+=x;
push(v,(tl<tr));
return;
}
int tm=(tl+tr)/2;
upd(l,r,x,v*2,tl,tm);
upd(l,r,x,v*2+1,tm+1,tr);
if(t[v*2].f<t[v*2+1].f){
t[v]=t[v*2+1];
}
else if(t[v*2].f>t[v*2+1].f){
t[v]=t[v*2];
}
else{
t[v]={t[v*2].f,t[v*2].s+t[v*2+1].s};
}
}
pair<int,int> get(int l,int r,int v=1,int tl=1,int tr=m){
push(v,(tl<tr));
if(tr<l||r<tl||l>r){
return {0,0};
}
if(l<=tl&&tr<=r){
return t[v];
}
int tm=(tl+tr)/2;
pair<int,int> a=get(l,r,v*2,tl,tm);
pair<int,int> b=get(l,r,v*2+1,tm+1,tr);
if(a.f<b.f){
return b;
}
else if(a.f>b.f){
return a;
}
else{
return {a.f,a.s+b.s};
}
}
void func(int i,int x,int y){
if(i+x-1<=m){
upd(i,i+x-1,y);
}
else{
upd(i,m,y);
upd(1,x-(m-i+1),y);
}
}
void tea(int v,int pr=0){
for(int i=0;i<len(g[v]);i++){
int to=g[v][i];
if(to==pr||k[to]){
continue;
}
tea(to,v);
}
for(int i=0;i<len(g[v]);i++){
int to=g[v][i];
if(to==pr||k[to]){
continue;
}
tea(to,v);
w.push_back({dm[to],e[to]});
}
w.clear();
for(int i=0;i<len(g[v]);i++){
int to=g[v][i];
if(to==pr||k[to]){
continue;
}
w.push_back({dm[to],e[to]});
}
sort(full(w));
reverse(full(w));
if(len(w)==1){
if(diam<w.back().f){
diam=w.back().f;
ans=0;
}
if(diam==w.back().f){
ans+=w.back().s;
}
}
else if(len(w)>1){
if(diam<w[0].f+w[1].f){
diam=w[0].f+w[1].f;
ans=0;
}
if(diam==w[0].f+w[1].f){
int cnt=w[0].s;
for(int i=1;i<len(w);i++){
if(w[i].f==w[1].f){
ans+=cnt*w[i].s;
}
if(w[i].f==w[0].f){
cnt+=w[i].s;
}
}
}
}
}
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();
d[0]=-1;
for(int i=1;i<=m;i++){
go(q[i]);
}
for(int i=1;i<=m;i++){
tea(q[i]);
if(i==1){
build();
continue;
}
int x=m/2;
int y=m-x;
func(i,x,-1);
if(y==x){
func(i+x-m*(i+x>m),y,1);
}
else{
func(i+x+1-m*(i+x+1>m),y-1,1);
}
r[i]=get(1,i-1);
if(diam<r[i].f+dm[q[i]]){
diam=r[i].f+dm[q[i]];
ans=0;
}
if(diam==r[i].f+dm[q[i]]){
if(m%2==0&&i-m/2>=1){
if(diam==dm[q[i]]+dm[q[i-m/2]]+m/2){
ans+=e[q[i]]*e[q[i-m/2]];
}
}
ans+=e[q[i]]*r[i].s;
}
//cout<<i<<" "<<q[i]<<" "<<r[i].f<<" "<<r[i].s<<" "<<e[q[i]]<<" "<<dm[q[i]]<<" "<<d[q[i]]<<" "<<m%2<<" "<<i-m/2<<" "<<diam<<" "<<dm[q[i-m/2]]<<" "<<e[q[i-m/2]]<<"\n";
}
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
|
shymbulak.cpp:243:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
243 | main(){
| ^~~~
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
14 ms |
23756 KB |
Output is correct |
| 2 |
Correct |
12 ms |
23880 KB |
Output is correct |
| 3 |
Correct |
12 ms |
23756 KB |
Output is correct |
| 4 |
Correct |
13 ms |
23868 KB |
Output is correct |
| 5 |
Incorrect |
13 ms |
23936 KB |
Output isn't correct |
| 6 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
13 ms |
24024 KB |
Output is correct |
| 2 |
Correct |
12 ms |
23884 KB |
Output is correct |
| 3 |
Correct |
13 ms |
24012 KB |
Output is correct |
| 4 |
Execution timed out |
1589 ms |
23884 KB |
Time limit exceeded |
| 5 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Execution timed out |
1595 ms |
30976 KB |
Time limit exceeded |
| 2 |
Halted |
0 ms |
0 KB |
- |
