// In the Name of Allah
#include<bits/stdc++.h>
using namespace std;
#define int long long
#define F first
#define S second
#define pii pair<int, int>
#define pb push_back
#define pp pop_back
#define all(x) x.begin(), x.end()
#define unq(x) sort(all(x)), x.resize(unique(all(x)) - x.begin())
const int N = 1e5 + 12, mod = 1'000'000'000 + 7;
vector<int> g[N];
int n, d, k[2], sz[N];
bool dpd[N], dp[N];
pii res[N];
void ip() {
cin >> n >> d;
for (int i = 1; i < n; i++) {
int u, v;
cin >> u >> v;
u--, v--;
g[u].pb(v);
g[v].pb(u);
}
}
void dfs1(int u, int par) {
sz[u] = 1;
for (auto i: g[u])
if (i != par) {
dfs1(i, u);
dpd[u] |= dpd[i];
sz[u] += sz[i];
}
dpd[u] = !dpd[u];
}
void dfs2(int u, int par, int c) {
c -= dpd[u];
dp[u] = (c != 0);
c = (u == 0)? 0 : !dp[u];
for (auto i: g[u])
if (i != par)
c += dpd[i];
for (auto i: g[u])
if (i != par)
dfs2(i, u, c);
}
void dfs3(int u, int par) {
int c = 0, v = 0;
for (auto i: g[u])
if (i != par) {
dfs3(i, u);
c += dpd[i];
if (dpd[i])
v = i;
}
if (!c) {
for (auto i: g[u])
if (i != par) {
res[u].F += res[i].S;
res[u].S += res[i].F;
}
res[u].F += k[1];
res[u].S += k[0];
}
else if (c == 1) {
res[u].F = (sz[u] - sz[v]) * n + res[v].S;
res[u].S = res[v].F;
}
else
res[u].F = sz[u] * n;
}
void solve() {
if (d == 1) {
dfs1(0, 0);
dp[0] = 1;
dfs2(0, 0, 2);
for (int i = 0; i < n; i++) {
dp[i] &= dpd[i];
k[dp[i]]++;
}
dfs3(0, 0);
cout << res[0].F % mod;
}
}
int32_t main() {
ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);
ip(), solve();
return 0;
}
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
4956 KB |
Output is correct |
2 |
Incorrect |
1 ms |
3164 KB |
Output isn't correct |
3 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Incorrect |
1 ms |
2912 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
4956 KB |
Output is correct |
2 |
Correct |
1 ms |
4956 KB |
Output is correct |
3 |
Correct |
1 ms |
4956 KB |
Output is correct |
4 |
Correct |
1 ms |
4956 KB |
Output is correct |
5 |
Correct |
2 ms |
4956 KB |
Output is correct |
6 |
Correct |
1 ms |
4956 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
4956 KB |
Output is correct |
2 |
Correct |
1 ms |
4956 KB |
Output is correct |
3 |
Correct |
1 ms |
4956 KB |
Output is correct |
4 |
Correct |
1 ms |
4956 KB |
Output is correct |
5 |
Correct |
2 ms |
4956 KB |
Output is correct |
6 |
Correct |
1 ms |
4956 KB |
Output is correct |
7 |
Correct |
1 ms |
5212 KB |
Output is correct |
8 |
Correct |
1 ms |
5184 KB |
Output is correct |
9 |
Correct |
1 ms |
5212 KB |
Output is correct |
10 |
Correct |
1 ms |
5212 KB |
Output is correct |
11 |
Correct |
1 ms |
5212 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
4956 KB |
Output is correct |
2 |
Correct |
1 ms |
4956 KB |
Output is correct |
3 |
Correct |
1 ms |
4956 KB |
Output is correct |
4 |
Correct |
1 ms |
4956 KB |
Output is correct |
5 |
Correct |
2 ms |
4956 KB |
Output is correct |
6 |
Correct |
1 ms |
4956 KB |
Output is correct |
7 |
Correct |
1 ms |
5212 KB |
Output is correct |
8 |
Correct |
1 ms |
5184 KB |
Output is correct |
9 |
Correct |
1 ms |
5212 KB |
Output is correct |
10 |
Correct |
1 ms |
5212 KB |
Output is correct |
11 |
Correct |
1 ms |
5212 KB |
Output is correct |
12 |
Correct |
47 ms |
13136 KB |
Output is correct |
13 |
Correct |
52 ms |
17252 KB |
Output is correct |
14 |
Correct |
25 ms |
9808 KB |
Output is correct |
15 |
Correct |
46 ms |
9944 KB |
Output is correct |
16 |
Correct |
36 ms |
10072 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
4956 KB |
Output is correct |
2 |
Correct |
1 ms |
4956 KB |
Output is correct |
3 |
Correct |
1 ms |
4956 KB |
Output is correct |
4 |
Correct |
1 ms |
4956 KB |
Output is correct |
5 |
Correct |
2 ms |
4956 KB |
Output is correct |
6 |
Correct |
1 ms |
4956 KB |
Output is correct |
7 |
Correct |
1 ms |
5212 KB |
Output is correct |
8 |
Correct |
1 ms |
5184 KB |
Output is correct |
9 |
Correct |
1 ms |
5212 KB |
Output is correct |
10 |
Correct |
1 ms |
5212 KB |
Output is correct |
11 |
Correct |
1 ms |
5212 KB |
Output is correct |
12 |
Correct |
1 ms |
5176 KB |
Output is correct |
13 |
Incorrect |
1 ms |
3136 KB |
Output isn't correct |
14 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
4956 KB |
Output is correct |
2 |
Correct |
1 ms |
4956 KB |
Output is correct |
3 |
Correct |
1 ms |
4956 KB |
Output is correct |
4 |
Correct |
1 ms |
4956 KB |
Output is correct |
5 |
Correct |
2 ms |
4956 KB |
Output is correct |
6 |
Correct |
1 ms |
4956 KB |
Output is correct |
7 |
Correct |
1 ms |
5212 KB |
Output is correct |
8 |
Correct |
1 ms |
5184 KB |
Output is correct |
9 |
Correct |
1 ms |
5212 KB |
Output is correct |
10 |
Correct |
1 ms |
5212 KB |
Output is correct |
11 |
Correct |
1 ms |
5212 KB |
Output is correct |
12 |
Correct |
47 ms |
13136 KB |
Output is correct |
13 |
Correct |
52 ms |
17252 KB |
Output is correct |
14 |
Correct |
25 ms |
9808 KB |
Output is correct |
15 |
Correct |
46 ms |
9944 KB |
Output is correct |
16 |
Correct |
36 ms |
10072 KB |
Output is correct |
17 |
Correct |
1 ms |
5176 KB |
Output is correct |
18 |
Incorrect |
1 ms |
3136 KB |
Output isn't correct |
19 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
4956 KB |
Output is correct |
2 |
Incorrect |
1 ms |
3164 KB |
Output isn't correct |
3 |
Halted |
0 ms |
0 KB |
- |