#include <iostream>
#include <vector>
#include <cmath>
#include <algorithm>
#include <string>
#include <map>
#include <unordered_map>
#include <set>
#include <unordered_set>
#include <queue>
#include <deque>
#include <list>
#include <iomanip>
#include <stdlib.h>
#include <time.h>
using namespace std;
typedef long long int ll;
typedef unsigned long long int ull;
typedef long double ld;
#define REP(i,a,b) for(ll i=a; i<b; i++)
#define pb push_back
#define mp make_pair
#define pl pair<ll,ll>
#define ff first
#define ss second
#define whole(x) x.begin(),x.end()
#define DEBUG(i) cout<<"Pedro Is The Master "<<i<<endl
#define INF 5000000000000000000LL
ll mod=1000000007LL;
template<class A=ll>
void Out(vector<A> a) {REP(i,0,a.size()) {cout<<a[i]<<" ";} cout<<endl;}
template<class A=ll>
void In(vector<A> &a, ll N) {A cur; REP(i,0,N) {cin>>cur; a.pb(cur);}}
class Matrix
{
public:
ll a,b,c,d;
Matrix() {a=1LL; b=0LL; c=0LL; d=1LL;}
Matrix(ll x, ll y, ll w, ll z) {a=x; b=y; c=w; d=z;}
Matrix operator *(Matrix X)
{
Matrix ANS(a*X.a+b*X.c,a*X.b+b*X.d,c*X.a+d*X.c,c*X.b+d*X.d);
ANS.a%=mod; ANS.b%=mod; ANS.c%=mod; ANS.d%=mod;
return ANS;
}
};
Matrix fastexp(Matrix A, ll e)
{
if(e==0LL) {Matrix id; return id;}
if(e%2LL==0LL) {Matrix V = fastexp(A,e/2LL); return (V*V);}
else {Matrix V=fastexp(A,e/2LL); return (V*V*A);}
}
class Tree
{
public:
ll N;
vector<ll> p;
vector<vector<ll> > sons;
vector<vector<ll> > adj;
ll root;
vector<bool> visited;
vector<ll> sub; //number of nodes in subtree
vector<ll> w,l,state;
Tree(vector<vector<ll> > ad, ll r=0LL)
{
N=ad.size(); root=r; adj=ad;
REP(i,0,N) {visited.pb(false);}
vector<ll> xx; REP(i,0,N) {sons.pb(xx); p.pb(-1); sub.pb(1LL);}
DFS_Build(r,r);
REP(i,0,N) {w.pb(-1); l.pb(-1); state.pb(-1);}
}
void Reset()
{
REP(i,0,N) {visited[i]=false;}
}
void DFS_Build(ll s, ll par)
{
p[s]=par;
visited[s]=true;
REP(i,0,adj[s].size())
{
if(adj[s][i]==par) {continue;}
sons[s].pb(adj[s][i]);
DFS_Build(adj[s][i],s);
sub[s]+=sub[adj[s][i]];
}
return;
}
void fE(ll s)
{
ll c;
REP(i,0,sons[s].size()) {c=sons[s][i]; fE(c);}
if(sons[s].size()==0) {w[s]=1LL; l[s]=0LL; state[s]=0LL; return;}
ll LC=0LL; ll lc=-1LL;
state[s]=0LL; REP(i,0,sons[s].size()) {c=sons[s][i]; if(state[c]==0LL) {LC++; lc=c;}}
if(LC>0LL) {state[s]=1LL;}
if(state[s]==0LL)
{
w[s]=0LL; REP(i,0,sons[s].size()) {c=sons[s][i]; w[s]+=l[c];}
w[s]++;
l[s]=sub[s]-w[s];
}
else if(LC>1LL)
{
w[s]=sub[s]; l[s]=0LL;
}
else
{
w[s]=sub[s]-sub[lc]+l[lc];
l[s]=sub[s]-w[s];
}
}
};
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
ll N,U; cin>>N>>U;
vector<vector<ll> > adj; vector<ll> xx; REP(i,0,N) {adj.pb(xx);}
pl cur;
REP(i,0,N-1)
{
cin>>cur.ff>>cur.ss; cur.ff--; cur.ss--;
adj[cur.ff].pb(cur.ss);
adj[cur.ss].pb(cur.ff);
}
ll A,B,C,D,E,F,G;
A=0LL; B=0LL; C=0LL; D=0LL; E=0LL; F=0LL; G=0LL;
REP(i,0,N)
{
Tree T(adj,i);
T.fE(i);
A+=T.w[i]; B+=T.l[i];
if(T.state[i]==1) {C++;} else {D++;}
if(i==0) {E=A; F=B; G=C;}
}
A%=mod; B%=mod;
Matrix M((C*N)%mod,A,(D*N)%mod,B);
M=fastexp(M,U-1LL);
pl las; las.ff=M.a*C+M.b*D; las.ss=M.c*C+M.d*D;
las.ff%=mod; las.ss%=mod;
ll ans=G*N*las.ff+E*las.ss;
ans%=mod; if(ans<0) {ans+=mod;}
cout<<ans<<endl;
return 0;
}
Compilation message
startrek.cpp: In member function 'void Tree::DFS_Build(ll, ll)':
startrek.cpp:20:33: warning: comparison of integer expressions of different signedness: 'll' {aka 'long long int'} and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
20 | #define REP(i,a,b) for(ll i=a; i<b; i++)
......
90 | REP(i,0,adj[s].size())
| ~~~~~~~~~~~~~~~~~
startrek.cpp:90:9: note: in expansion of macro 'REP'
90 | REP(i,0,adj[s].size())
| ^~~
startrek.cpp: In member function 'void Tree::fE(ll)':
startrek.cpp:20:33: warning: comparison of integer expressions of different signedness: 'll' {aka 'long long int'} and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
20 | #define REP(i,a,b) for(ll i=a; i<b; i++)
......
103 | REP(i,0,sons[s].size()) {c=sons[s][i]; fE(c);}
| ~~~~~~~~~~~~~~~~~~
startrek.cpp:103:9: note: in expansion of macro 'REP'
103 | REP(i,0,sons[s].size()) {c=sons[s][i]; fE(c);}
| ^~~
startrek.cpp:20:33: warning: comparison of integer expressions of different signedness: 'll' {aka 'long long int'} and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
20 | #define REP(i,a,b) for(ll i=a; i<b; i++)
......
106 | state[s]=0LL; REP(i,0,sons[s].size()) {c=sons[s][i]; if(state[c]==0LL) {LC++; lc=c;}}
| ~~~~~~~~~~~~~~~~~~
startrek.cpp:106:23: note: in expansion of macro 'REP'
106 | state[s]=0LL; REP(i,0,sons[s].size()) {c=sons[s][i]; if(state[c]==0LL) {LC++; lc=c;}}
| ^~~
startrek.cpp:20:33: warning: comparison of integer expressions of different signedness: 'll' {aka 'long long int'} and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
20 | #define REP(i,a,b) for(ll i=a; i<b; i++)
......
110 | w[s]=0LL; REP(i,0,sons[s].size()) {c=sons[s][i]; w[s]+=l[c];}
| ~~~~~~~~~~~~~~~~~~
startrek.cpp:110:23: note: in expansion of macro 'REP'
110 | w[s]=0LL; REP(i,0,sons[s].size()) {c=sons[s][i]; w[s]+=l[c];}
| ^~~
startrek.cpp: In function 'int main()':
startrek.cpp:139:18: warning: variable 'F' set but not used [-Wunused-but-set-variable]
139 | ll A,B,C,D,E,F,G;
| ^
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
384 KB |
Output is correct |
2 |
Correct |
272 ms |
760 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
0 ms |
384 KB |
Output is correct |
2 |
Correct |
0 ms |
384 KB |
Output is correct |
3 |
Correct |
1 ms |
384 KB |
Output is correct |
4 |
Correct |
0 ms |
384 KB |
Output is correct |
5 |
Correct |
0 ms |
384 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
384 KB |
Output is correct |
2 |
Correct |
3 ms |
384 KB |
Output is correct |
3 |
Correct |
4 ms |
384 KB |
Output is correct |
4 |
Correct |
3 ms |
384 KB |
Output is correct |
5 |
Correct |
4 ms |
384 KB |
Output is correct |
6 |
Correct |
4 ms |
384 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
384 KB |
Output is correct |
2 |
Correct |
3 ms |
384 KB |
Output is correct |
3 |
Correct |
4 ms |
384 KB |
Output is correct |
4 |
Correct |
3 ms |
384 KB |
Output is correct |
5 |
Correct |
4 ms |
384 KB |
Output is correct |
6 |
Correct |
4 ms |
384 KB |
Output is correct |
7 |
Correct |
267 ms |
760 KB |
Output is correct |
8 |
Correct |
263 ms |
640 KB |
Output is correct |
9 |
Correct |
231 ms |
640 KB |
Output is correct |
10 |
Correct |
276 ms |
760 KB |
Output is correct |
11 |
Correct |
265 ms |
660 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
384 KB |
Output is correct |
2 |
Correct |
3 ms |
384 KB |
Output is correct |
3 |
Correct |
4 ms |
384 KB |
Output is correct |
4 |
Correct |
3 ms |
384 KB |
Output is correct |
5 |
Correct |
4 ms |
384 KB |
Output is correct |
6 |
Correct |
4 ms |
384 KB |
Output is correct |
7 |
Correct |
267 ms |
760 KB |
Output is correct |
8 |
Correct |
263 ms |
640 KB |
Output is correct |
9 |
Correct |
231 ms |
640 KB |
Output is correct |
10 |
Correct |
276 ms |
760 KB |
Output is correct |
11 |
Correct |
265 ms |
660 KB |
Output is correct |
12 |
Execution timed out |
1053 ms |
35184 KB |
Time limit exceeded |
13 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
384 KB |
Output is correct |
2 |
Correct |
3 ms |
384 KB |
Output is correct |
3 |
Correct |
4 ms |
384 KB |
Output is correct |
4 |
Correct |
3 ms |
384 KB |
Output is correct |
5 |
Correct |
4 ms |
384 KB |
Output is correct |
6 |
Correct |
4 ms |
384 KB |
Output is correct |
7 |
Correct |
267 ms |
760 KB |
Output is correct |
8 |
Correct |
263 ms |
640 KB |
Output is correct |
9 |
Correct |
231 ms |
640 KB |
Output is correct |
10 |
Correct |
276 ms |
760 KB |
Output is correct |
11 |
Correct |
265 ms |
660 KB |
Output is correct |
12 |
Correct |
0 ms |
384 KB |
Output is correct |
13 |
Correct |
270 ms |
660 KB |
Output is correct |
14 |
Correct |
1 ms |
384 KB |
Output is correct |
15 |
Correct |
0 ms |
384 KB |
Output is correct |
16 |
Correct |
4 ms |
384 KB |
Output is correct |
17 |
Correct |
3 ms |
384 KB |
Output is correct |
18 |
Correct |
3 ms |
384 KB |
Output is correct |
19 |
Correct |
3 ms |
384 KB |
Output is correct |
20 |
Correct |
3 ms |
384 KB |
Output is correct |
21 |
Correct |
266 ms |
640 KB |
Output is correct |
22 |
Correct |
268 ms |
640 KB |
Output is correct |
23 |
Correct |
232 ms |
760 KB |
Output is correct |
24 |
Correct |
273 ms |
660 KB |
Output is correct |
25 |
Correct |
274 ms |
760 KB |
Output is correct |
26 |
Correct |
271 ms |
640 KB |
Output is correct |
27 |
Correct |
261 ms |
760 KB |
Output is correct |
28 |
Correct |
150 ms |
632 KB |
Output is correct |
29 |
Correct |
281 ms |
656 KB |
Output is correct |
30 |
Correct |
267 ms |
760 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
384 KB |
Output is correct |
2 |
Correct |
3 ms |
384 KB |
Output is correct |
3 |
Correct |
4 ms |
384 KB |
Output is correct |
4 |
Correct |
3 ms |
384 KB |
Output is correct |
5 |
Correct |
4 ms |
384 KB |
Output is correct |
6 |
Correct |
4 ms |
384 KB |
Output is correct |
7 |
Correct |
267 ms |
760 KB |
Output is correct |
8 |
Correct |
263 ms |
640 KB |
Output is correct |
9 |
Correct |
231 ms |
640 KB |
Output is correct |
10 |
Correct |
276 ms |
760 KB |
Output is correct |
11 |
Correct |
265 ms |
660 KB |
Output is correct |
12 |
Execution timed out |
1053 ms |
35184 KB |
Time limit exceeded |
13 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
384 KB |
Output is correct |
2 |
Correct |
272 ms |
760 KB |
Output is correct |
3 |
Correct |
0 ms |
384 KB |
Output is correct |
4 |
Correct |
0 ms |
384 KB |
Output is correct |
5 |
Correct |
1 ms |
384 KB |
Output is correct |
6 |
Correct |
0 ms |
384 KB |
Output is correct |
7 |
Correct |
0 ms |
384 KB |
Output is correct |
8 |
Correct |
1 ms |
384 KB |
Output is correct |
9 |
Correct |
3 ms |
384 KB |
Output is correct |
10 |
Correct |
4 ms |
384 KB |
Output is correct |
11 |
Correct |
3 ms |
384 KB |
Output is correct |
12 |
Correct |
4 ms |
384 KB |
Output is correct |
13 |
Correct |
4 ms |
384 KB |
Output is correct |
14 |
Correct |
267 ms |
760 KB |
Output is correct |
15 |
Correct |
263 ms |
640 KB |
Output is correct |
16 |
Correct |
231 ms |
640 KB |
Output is correct |
17 |
Correct |
276 ms |
760 KB |
Output is correct |
18 |
Correct |
265 ms |
660 KB |
Output is correct |
19 |
Execution timed out |
1053 ms |
35184 KB |
Time limit exceeded |
20 |
Halted |
0 ms |
0 KB |
- |