//0 1 1 0 1
//0 1 0 0 1
//1 0 0 1 1
//0 1 1 0 1
#include <bits/stdc++.h>
#pragma GCC optimize("Ofast,unroll-loops")
// #pragma GCC target("avx2")
using namespace std;
#define F first
#define S second
#define pb push_back
#define sze size()
#define all(x) x.begin() , x.end()
#define wall__ cout << "--------------------------------------\n";
#define kids int mid = (tl + tr) >> 1, cl = v << 1, cr = v << 1 | 1
#define file_io freopen("input.cpp", "r", stdin); freopen("output.cpp", "w", stdout);
typedef long long ll;
typedef long double dl;
typedef pair < int , int > pii;
typedef pair < int , ll > pil;
typedef pair < ll , int > pli;
typedef pair < ll , ll > pll;
typedef pair < int , pii > piii;
typedef pair < ll, pll > plll;
const ll N = 2e5 + 10;
const ll mod = 1e9 + 7;
const ll inf = 2e16;
const ll INF = 1e9 + 10;
const ll lg = 32;
int n, k;
vector < pii > g[N], ord;
int sub[N], flag[N], bit[N];
pii h[N];
ll ans = 0;
void pre_calc (int v, int p) {
sub[v] = 1;
for (auto e : g[v]) {
int u = e.F;
if (flag[u] || u == p) continue;
pre_calc(u, v);
sub[v] += sub[u];
}
}
int find_cen (int v, int p, int s) {
for (auto e : g[v]) {
int u = e.F;
if (u == p || flag[u]) continue;
if (sub[u] > s / 2) return find_cen(u, v, s);
}
return v;
}
void dfs (int v, int p) {
// cout << v << " , " << p << '\n';
sub[v] = 1;
if (p != 0) ord.pb({h[v].S, h[v].F});
for (auto e : g[v]) {
int u = e.F;
if (flag[u] || u == p) continue;
h[u] = {h[v].F + 1, max(h[v].S, e.S)};
dfs(u, v);
sub[u] += sub[v];
}
}
inline int read (int idx) {
int res = 0;
for (; idx > 0; idx -= (idx & -idx)) res += bit[idx];
return res;
}
inline void upd (int idx, int val, int s) {
for (; idx <= s; idx += (idx & -idx)) bit[idx] += val;
}
ll calc (int root, int t) {
// cout << root << " : \n";
ord.clear();
int pp = 0;
if (t) pp = -1;
dfs (root, pp);
for (int i = 0; i <= sub[root]; i++) bit[i] = 0;
sort(all(ord));
// cout << "& \n";
ll res = 0;
for (auto e : ord) {
// cout << e.F << " - " << e.S << '\n';
int w = e.F, l = e.S;
int l2 = w - k - l;
if (l2 >= 0) {
res += read(l2);
if (t == 0) ++res;
}
if (l > 0) upd(l, 1, sub[root]);
}
// cout << "-- " << res << '\n';
// wall__
return res;
}
void centree (int v) {
// cout << v << '\n';
pre_calc(v, 0);
// cout << "*\n";
int cen = find_cen(v, 0, sub[v]);
// cout << "cen = " << cen << '\n';
h[cen] = {0, 0};
ans += calc(cen, 0);
// cout << "* " << ans << '\n';
// cout << "* =\n";
flag[cen] = 1;
for (auto e : g[cen]) {
int u = e.F;
if (flag[u]) continue;
h[u] = {1, e.S};
ans -= calc(u, 1);
// cout << "* " << ans << '\n';
centree(u);
}
}
void solve () {
cin >> n >> k;
for (int i = 1; i < n; i++) {
int v, u, w; cin >> v >> u >> w;
g[v].pb({u, w});
g[u].pb({v, w});
}
centree(1);
cout << ans * 2ll << '\n';
}
int main() {
// ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
int t = 1;
// cin >> t;
while (t--) {solve();}
return 0;
}
/*
*/
//shrek is love;
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
2 ms |
4948 KB |
Output is correct |
| 2 |
Correct |
2 ms |
4948 KB |
Output is correct |
| 3 |
Incorrect |
2 ms |
4948 KB |
Output isn't correct |
| 4 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
2 ms |
4948 KB |
Output is correct |
| 2 |
Correct |
2 ms |
4948 KB |
Output is correct |
| 3 |
Incorrect |
2 ms |
4948 KB |
Output isn't correct |
| 4 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
2 ms |
4948 KB |
Output is correct |
| 2 |
Correct |
2 ms |
4948 KB |
Output is correct |
| 3 |
Incorrect |
2 ms |
4948 KB |
Output isn't correct |
| 4 |
Halted |
0 ms |
0 KB |
- |
