# include <bits/stdc++.h>
using namespace std;
using ll = long long;
using db = long double; // or double, if TL is tight
using str = string; // yay python!
// pairs
using pii = pair<int,int>;
using pl = pair<ll,ll>;
using pd = pair<db,db>;
#define mp make_pair
#define f first
#define s second
#define tcT template<class T
#define tcTU tcT, class U
// ^ lol this makes everything look weird but I'll try it
tcT> using V = vector<T>;
tcT, size_t SZ> using AR = array<T,SZ>;
using vi = V<int>;
using vb = V<bool>;
using vl = V<ll>;
using vd = V<db>;
using vs = V<str>;
using vpi = V<pii>;
using vpl = V<pl>;
using vpd = V<pd>;
// vectors
// oops size(x), rbegin(x), rend(x) need C++17
#define sz(x) int((x).size())
#define bg(x) begin(x)
#define all(x) bg(x), end(x)
#define rall(x) x.rbegin(), x.rend()
#define sor(x) sort(all(x))
#define rsz resize
#define ins insert
#define pb push_back
#define eb emplace_back
#define ft front()
#define bk back()
#define lb lower_bound
#define ub upper_bound
#define FOR(i,a,b) for (int i = (a); i < (b); ++i)
#define F0R(i,a) FOR(i,0,a)
#define ROF(i,a,b) for (int i = (b)-1; i >= (a); --i)
#define R0F(i,a) ROF(i,0,a)
#define rep(a) F0R(_,a)
#define each(a,x) for (auto& a: x)
const int MOD = 998244353;
const int MX = 2e5+5;
const ll BIG = 1e18; // not too close to LLONG_MAX
const db PI = acos((db)-1);
const int dx[4]{1,0,-1,0}, dy[4]{0,1,0,-1}; // for every grid problem!!
mt19937 rng((uint32_t)chrono::steady_clock::now().time_since_epoch().count());
template<class T> using pqg = priority_queue<T,vector<T>,greater<T>>;
struct DSU {
vi e; void init(int N) { e = vi(N,-1); }
int get(int x) { return e[x] < 0 ? x : e[x] = get(e[x]); }
bool sameSet(int a, int b) { return get(a) == get(b); }
int size(int x) { return -e[get(x)]; }
bool unite(int x, int y) { // union by size
x = get(x), y = get(y); if (x == y) return 0;
if (e[x] > e[y]) swap(x,y);
e[x] += e[y]; e[y] = x; return 1;
}
};
/*
inline namespace Helpers {
//////////// is_iterable
// https://stackoverflow.com/questions/13830158/check-if-a-variable-type-is-iterable
// this gets used only when we can call begin() and end() on that type
tcT, class = void> struct is_iterable : false_type {};
tcT> struct is_iterable<T, void_t<decltype(begin(declval<T>())),
decltype(end(declval<T>()))
>
> : true_type {};
tcT> constexpr bool is_iterable_v = is_iterable<T>::value;
//////////// is_readable
tcT, class = void> struct is_readable : false_type {};
tcT> struct is_readable<T,
typename std::enable_if_t<
is_same_v<decltype(cin >> declval<T&>()), istream&>
>
> : true_type {};
tcT> constexpr bool is_readable_v = is_readable<T>::value;
//////////// is_printable
// // https://nafe.es/posts/2020-02-29-is-printable/
tcT, class = void> struct is_printable : false_type {};
tcT> struct is_printable<T,
typename std::enable_if_t<
is_same_v<decltype(cout << declval<T>()), ostream&>
>
> : true_type {};
tcT> constexpr bool is_printable_v = is_printable<T>::value;
}*/
using ll = long long;
using db = long double; // or double, if TL is tight
using str = string; // yay python!
// pairs
using pii = pair<int,int>;
using pl = pair<ll,ll>;
using pd = pair<db,db>;
#define mp make_pair
#define f first
#define s second
#define tcT template<class T
#define tcTU tcT, class U
// ^ lol this makes everything look weird but I'll try it
tcT> using V = vector<T>;
tcT, size_t SZ> using AR = array<T,SZ>;
using vi = V<int>;
using vb = V<bool>;
using vl = V<ll>;
using vd = V<db>;
using vs = V<str>;
using vpi = V<pii>;
using vpl = V<pl>;
using vpd = V<pd>;
// vectors
// oops size(x), rbegin(x), rend(x) need C++17
#define sz(x) int((x).size())
#define bg(x) begin(x)
#define all(x) bg(x), end(x)
#define rall(x) x.rbegin(), x.rend()
#define sor(x) sort(all(x))
#define rsz resize
#define ins insert
#define pb push_back
#define eb emplace_back
#define ft front()
#define bk back()
#define lb lower_bound
#define ub upper_bound
#define FOR(i,a,b) for (int i = (a); i < (b); ++i)
#define F0R(i,a) FOR(i,0,a)
#define ROF(i,a,b) for (int i = (b)-1; i >= (a); --i)
#define R0F(i,a) ROF(i,0,a)
#define rep(a) F0R(_,a)
#define each(a,x) for (auto& a: x)
template<class T> using pqg = priority_queue<T,vector<T>,greater<T>>;
/*
inline namespace Helpers {
//////////// is_iterable
// https://stackoverflow.com/questions/13830158/check-if-a-variable-type-is-iterable
// this gets used only when we can call begin() and end() on that type
tcT, class = void> struct is_iterable : false_type {};
tcT> struct is_iterable<T, void_t<decltype(begin(declval<T>())),
decltype(end(declval<T>()))
>
> : true_type {};
tcT> constexpr bool is_iterable_v = is_iterable<T>::value;
//////////// is_readable
tcT, class = void> struct is_readable : false_type {};
tcT> struct is_readable<T,
typename std::enable_if_t<
is_same_v<decltype(cin >> declval<T&>()), istream&>
>
> : true_type {};
tcT> constexpr bool is_readable_v = is_readable<T>::value;
//////////// is_printable
// // https://nafe.es/posts/2020-02-29-is-printable/
tcT, class = void> struct is_printable : false_type {};
tcT> struct is_printable<T,
typename std::enable_if_t<
is_same_v<decltype(cout << declval<T>()), ostream&>
>
> : true_type {};
tcT> constexpr bool is_printable_v = is_printable<T>::value;
}*/
const int N = 3e5 + 5;
int t,n,a[N],b[N],p[N],fix[N],fix1[N],sz[N],m, lv[N];
int x[N],y[N];
vector <int> v[N],con[N],v1[N];
int par[N][20],tin, in[N],out[N],mn[N];
multiset <int> s;
int get_col(int a) {
if (a == p[a]) return a;
else return p[a] = get_col(p[a]);
}
void col(int a, int b) {
a = get_col(a);
b = get_col(b);
if (a == b) return ;
if (sz[a] < sz[b]) swap(a,b);
p[b] = a;
sz[a] += sz[b];
sz[b] = 0;
}
void init() {
for (int i = 1; i <= n; i++) {
p[i] = i;
sz[i] = 1;
}
}
void dfs(int a, int p) {
lv[a] = lv[p] + 1;
par[a][0] = p;
tin++;
in[a] = tin;
for (int i = 1; i <= 18; i++) {
if (par[a][i - 1]) par[a][i] = par[par[a][i - 1]][i - 1];
}
for (int to : v[a]) {
if (to == p) continue;
dfs(to,a);
}
out[a] = tin;
}
int upper(int a, int b) {
return (in[a] <= in[b] && out[a] >= out[b]);
}
int lca(int a, int b) {
if (upper(a,b)) return a;
for (int i = 18; i >= 0; i--) {
if (par[a][i] && !upper(par[a][i],b)) a = par[a][i];
}
return par[a][0];
}
void dfs1(int a, int p) {
mn[a] = 1e9;
for (int x : con[a]) mn[a] = min(mn[a], lv[x]);
for (int to : v[a]) {
if (to == p) continue;
dfs1(to,a);
if (p && mn[to] <= lv[p]) col(a,to);
mn[a] = min(mn[a], mn[to]);
}
}
void check(int a, int p) {
fix1[a] = 1;
for (int to : v1[a]) {
if (to == p) continue;
if (fix1[to]) {
cout<<0<<"\n"; exit(0);
}
check(to, a);
}
}
main() {
std::ios_base::sync_with_stdio(false),cin.tie(0),cout.tie(0);
cin>>n>>m;
init();
for (int i = 1; i <= n - 1; i++) {
int a, b;
cin>>x[i]>>y[i];
v[x[i]].pb(y[i]);
v[y[i]].pb(x[i]);
}
for (int i = 1; i <= m; i++) {
cin>>a[i]>>b[i];
}
dfs(1,0);
for (int i = 1; i <= m; i++) {
int lc = lca(a[i],b[i]);
if (lv[a[i]] - lv[lc] >= 2) con[a[i]].pb(lc);
if (lv[b[i]] - lv[lc] >= 2) con[b[i]].pb(lc);
}
dfs1(1,0);
for (int i = 1; i <= m; i++) {
int lc = lca(a[i],b[i]); if(lc == a[i] || lc == b[i]) continue;
int aa = get_col(a[i]); int bb = get_col(b[i]);
v1[aa].pb(bb); v1[bb].pb(aa);
if (get_col(a[i]) == get_col(b[i])) {
cout<<0<<"\n";
exit(0);
}
}
for (int i = 1; i <= n; i++) {
if (!fix1[i]) {
check(i, 0);
}
}
for (int i = 1; i <= m; i++) {
int lc = lca(a[i],b[i]); if (lc == a[i] || lc == b[i]) continue;
col(a[i],b[i]);
}
set <int> st;
for (int i = 2; i <= n; i++) {
st.insert(get_col(i));
}
long long x = 1, mod = 1e9 + 7;
for (int i = 1; i <= (int)st.size(); i++) {
x *= 2LL; x %= mod;
}
cout<<x<<"\n";
}
Compilation message
usmjeri.cpp:251:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
251 | main() {
| ^~~~
usmjeri.cpp: In function 'int main()':
usmjeri.cpp:256:10: warning: unused variable 'a' [-Wunused-variable]
256 | int a, b;
| ^
usmjeri.cpp:256:13: warning: unused variable 'b' [-Wunused-variable]
256 | int a, b;
| ^
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
104 ms |
50132 KB |
Output is correct |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
255 ms |
105428 KB |
Output is correct |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Incorrect |
14 ms |
21588 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Incorrect |
12 ms |
21588 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Incorrect |
13 ms |
22228 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Incorrect |
15 ms |
22356 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Incorrect |
353 ms |
70336 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Incorrect |
395 ms |
73640 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Incorrect |
369 ms |
74084 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Incorrect |
345 ms |
74768 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
