#include<bits/stdc++.h>
using namespace std;
const long long inf = (long long) 1e18 + 10;
const int inf1 = (int) 1e9 + 10;
#define int long long
#define dbl long double
#define endl '\n'
#define sc second
#define fr first
#define mp make_pair
#define pb push_back
#define all(x) x.begin(), x.end()
const int maxn = 5e5+10;
const int mod = 1e9+7;
int n, d, SL, SW, dpw[maxn][2], dpl[maxn][2];
vector<int> g[maxn];
void dfs1(int u, int ant) {
dpw[u][1] = SW*dpw[u][0] + SL*(dpw[u][0]+dpl[u][0]); dpw[u][1]%= mod;
dpl[u][1] = SW*dpl[u][0]; dpl[u][1]%= mod;
int qtl = 0;
for(auto v : g[u]) if(v != ant) {
qtl+= dpl[v][0];
dfs1(v,u);
}
for(auto v : g[u]) if(v != ant) {
qtl-= dpl[v][0];
if(qtl) {
dpw[u][1]+= dpw[v][1]+dpl[v][1]; dpw[u][1]%= mod;
dpl[u][1]+= 0;
}
else {
dpw[u][1]+= dpl[v][1]; dpw[u][1]%= mod;
dpl[u][1]+= dpw[v][1]; dpl[u][1]%= mod;
}
qtl+= dpl[v][0];
}
}
map<int,int> wp[maxn];
int solwp(int u, int ant) {
if(wp[u].count(ant)) return wp[u][ant];
wp[u][ant] = 0;
for(auto v : g[u]) if(v != ant) {
if(solwp(v,u) == 0) wp[u][ant] = 1;
}
return wp[u][ant];
}
void dfs0(int u, int ant) {
dpw[u][0] = 0;
for(auto v : g[u]) if(v != ant) {
dfs0(v,u);
}
for(auto v : g[u]) if(v != ant) {
if(solwp(v,u) == 0) dpw[u][0] = 1;
}
dpl[u][0] = 1-dpw[u][0];
}
void solve() {
cin >> n >> d;
for(int i = 1; i <= n-1; i++) {
int u,v; cin >> u >> v;
g[u].pb(v);
g[v].pb(u);
}
for(int i = 1; i <= n; i++) {
if(solwp(i,0) == 1) SW++;
else SL++;
}
dfs0(1,0);
dfs1(1,0);
cout << dpw[1][1] << endl;
}
int32_t main() {
ios::sync_with_stdio(false); cin.tie(0);
// freopen("in.in", "r", stdin);
// freopen("out.out", "w", stdout);
int tt = 1;
// cin >> tt;
while(tt--) {
solve();
}
}
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
23 ms |
35540 KB |
Output is correct |
2 |
Incorrect |
20 ms |
35736 KB |
Output isn't correct |
3 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Incorrect |
17 ms |
35476 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
18 ms |
35564 KB |
Output is correct |
2 |
Correct |
18 ms |
35576 KB |
Output is correct |
3 |
Correct |
19 ms |
35472 KB |
Output is correct |
4 |
Correct |
19 ms |
35588 KB |
Output is correct |
5 |
Correct |
17 ms |
35540 KB |
Output is correct |
6 |
Correct |
17 ms |
35492 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
18 ms |
35564 KB |
Output is correct |
2 |
Correct |
18 ms |
35576 KB |
Output is correct |
3 |
Correct |
19 ms |
35472 KB |
Output is correct |
4 |
Correct |
19 ms |
35588 KB |
Output is correct |
5 |
Correct |
17 ms |
35540 KB |
Output is correct |
6 |
Correct |
17 ms |
35492 KB |
Output is correct |
7 |
Correct |
23 ms |
35868 KB |
Output is correct |
8 |
Correct |
22 ms |
35808 KB |
Output is correct |
9 |
Correct |
26 ms |
35752 KB |
Output is correct |
10 |
Correct |
22 ms |
35796 KB |
Output is correct |
11 |
Correct |
23 ms |
35796 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
18 ms |
35564 KB |
Output is correct |
2 |
Correct |
18 ms |
35576 KB |
Output is correct |
3 |
Correct |
19 ms |
35472 KB |
Output is correct |
4 |
Correct |
19 ms |
35588 KB |
Output is correct |
5 |
Correct |
17 ms |
35540 KB |
Output is correct |
6 |
Correct |
17 ms |
35492 KB |
Output is correct |
7 |
Correct |
23 ms |
35868 KB |
Output is correct |
8 |
Correct |
22 ms |
35808 KB |
Output is correct |
9 |
Correct |
26 ms |
35752 KB |
Output is correct |
10 |
Correct |
22 ms |
35796 KB |
Output is correct |
11 |
Correct |
23 ms |
35796 KB |
Output is correct |
12 |
Correct |
240 ms |
64988 KB |
Output is correct |
13 |
Correct |
213 ms |
69908 KB |
Output is correct |
14 |
Execution timed out |
1080 ms |
45688 KB |
Time limit exceeded |
15 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
18 ms |
35564 KB |
Output is correct |
2 |
Correct |
18 ms |
35576 KB |
Output is correct |
3 |
Correct |
19 ms |
35472 KB |
Output is correct |
4 |
Correct |
19 ms |
35588 KB |
Output is correct |
5 |
Correct |
17 ms |
35540 KB |
Output is correct |
6 |
Correct |
17 ms |
35492 KB |
Output is correct |
7 |
Correct |
23 ms |
35868 KB |
Output is correct |
8 |
Correct |
22 ms |
35808 KB |
Output is correct |
9 |
Correct |
26 ms |
35752 KB |
Output is correct |
10 |
Correct |
22 ms |
35796 KB |
Output is correct |
11 |
Correct |
23 ms |
35796 KB |
Output is correct |
12 |
Correct |
17 ms |
35540 KB |
Output is correct |
13 |
Incorrect |
19 ms |
35716 KB |
Output isn't correct |
14 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
18 ms |
35564 KB |
Output is correct |
2 |
Correct |
18 ms |
35576 KB |
Output is correct |
3 |
Correct |
19 ms |
35472 KB |
Output is correct |
4 |
Correct |
19 ms |
35588 KB |
Output is correct |
5 |
Correct |
17 ms |
35540 KB |
Output is correct |
6 |
Correct |
17 ms |
35492 KB |
Output is correct |
7 |
Correct |
23 ms |
35868 KB |
Output is correct |
8 |
Correct |
22 ms |
35808 KB |
Output is correct |
9 |
Correct |
26 ms |
35752 KB |
Output is correct |
10 |
Correct |
22 ms |
35796 KB |
Output is correct |
11 |
Correct |
23 ms |
35796 KB |
Output is correct |
12 |
Correct |
240 ms |
64988 KB |
Output is correct |
13 |
Correct |
213 ms |
69908 KB |
Output is correct |
14 |
Execution timed out |
1080 ms |
45688 KB |
Time limit exceeded |
15 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
23 ms |
35540 KB |
Output is correct |
2 |
Incorrect |
20 ms |
35736 KB |
Output isn't correct |
3 |
Halted |
0 ms |
0 KB |
- |