#include <bits/stdc++.h>
using namespace std;
#define lli long long int
#define mp make_pair
#define pb push_back
#define eb emplace_back
#define pii pair <int, int>
#define X first
#define Y second
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
void abc() {cout << endl;}
template <typename T, typename ...U> void abc(T a, U ...b) {
cout << a << ' ', abc(b...);
}
template <typename T> void printv(T l, T r) {
while (l != r) cout << *l << " \n"[++l == r];
}
template <typename A, typename B> istream& operator >> (istream& o, pair<A, B> &a) {
return o >> a.X >> a.Y;
}
template <typename A, typename B> ostream& operator << (ostream& o, pair<A, B> a) {
return o << '(' << a.X << ", " << a.Y << ')';
}
template <typename T> ostream& operator << (ostream& o, vector<T> a) {
if (a.empty())
return o << "{}";
bool is = false;
for (T i : a) {o << (is ? ' ' : '{'), is = true, o << i;}
return o << '}';
}
template <typename T> struct vv : vector <vector <T>> {
vv(int n, int m, T v) : vector <vector <T>> (n, vector <T>(m, v)) {}
vv() {}
};
template <typename T> struct vvv : vector <vv <T>> {
vvv(int n, int m, int k, T v) : vector <vv <T>> (n, vv <T>(m, k, v)) {}
vvv() {}
};
#ifdef Doludu
#define test(args...) abc("[" + string(#args) + "]", args)
#define owo freopen("input.txt", "r", stdin), freopen("output.txt", "w", stdout)
#else
#define test(args...) void(0)
#define owo ios::sync_with_stdio(false); cin.tie(0)
#endif
const int mod = 1e9 + 7, N = 100010, logN = 17, K = 350, M = N * 40;
int k;
vector <pii> adj[N];
int sz[N];
bool vis[N];
void dfssz(int v, int pa) {
sz[v] = 1;
for (auto [u, w] : adj[v]) if (u != pa && !vis[u]) {
dfssz(u, v);
sz[v] += sz[u];
}
}
int dfscen(int v, int pa, int n) {
for (auto [u, w] : adj[v]) if (u != pa && !vis[u] && sz[u] * 2 > n)
return dfscen(u, v, n);
return v;
}
struct BIT {
int val[N];
vector <int> move;
BIT () {
fill(val, val + N, 0);
}
void add(int p, int v) {
p += 3;
for (int i = p; i < N; i += i & (-i))
val[i] += v, move.pb(i);
}
int query(int p) {
p += 3;
int ans = 0;
for (int i = p; i > 0; i -= i & (-i))
ans += val[i];
return ans;
}
void reset() {
for (int i : move)
val[i] = 0;
move.clear();
}
} bit;
lli ans;
// max(mx[a], mx[b]) - dp[a] >= k + dp[b]
// mx[a] > mx[b] -> mx[a] - dp[a] >= k + dp[b]
// k + dep[b] <= mx[a] - dep[a]
vector <int> all, cc;
int mx[N], dep[N];
lli calc() {
sort(all(cc), [&](int i, int j) {
return mx[i] < mx[j];
});
lli cur = 0;
for (int i : cc) {
cur += bit.query(mx[i] - dep[i]);
bit.add(k + dep[i], 1);
}
bit.reset();
return cur;
}
void dfsans(int v, int pa) {
if (~pa)
cc.pb(v);
else
mx[v] = dep[v] = 0;
for (auto [u, w] : adj[v]) if (u != pa && !vis[u]) {
mx[u] = max(mx[u], w);
dep[u] = dep[v] + 1;
if (mx[u] - dep[u] >= k)
ans++;
dfsans(u, v);
if (pa == -1) {
ans -= calc();
for (int i : cc)
all.pb(i);
cc.clear();
}
}
if (pa == -1) {
swap(all, cc);
ans += calc();
cc.clear();
}
}
void dfscd(int v, int pa) {
dfssz(v, pa);
int c = dfscen(v, pa, sz[v]);
vis[c] = true;
dfsans(c, -1);
for (auto [u, w] : adj[c]) if (!vis[u])
dfscd(u, c);
}
int main () {
owo;
int n;
cin >> n >> k;
for (int i = 0, u, v, w; i < n - 1; ++i) {
cin >> u >> v >> w, --u, --v;
adj[u].eb(v, w), adj[v].eb(u, w);
}
dfscd(0, -1);
cout << ans * 2 << endl;
}
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
2 ms |
3020 KB |
Output is correct |
| 2 |
Correct |
1 ms |
3020 KB |
Output is correct |
| 3 |
Incorrect |
2 ms |
3000 KB |
Output isn't correct |
| 4 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
1 ms |
3020 KB |
Output is correct |
| 2 |
Correct |
1 ms |
3020 KB |
Output is correct |
| 3 |
Incorrect |
2 ms |
3020 KB |
Output isn't correct |
| 4 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
2 ms |
3020 KB |
Output is correct |
| 2 |
Correct |
1 ms |
3020 KB |
Output is correct |
| 3 |
Incorrect |
2 ms |
3000 KB |
Output isn't correct |
| 4 |
Halted |
0 ms |
0 KB |
- |
