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treap4.cpp
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treap4.cpp
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/*
poj743
*/
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<cstdlib>
using namespace std;
const int maxN = 10005, maxM = 20005;
int n, m, total, answer, e[maxN], w[maxM], son[maxM], nxt[maxM];
struct node {
node* son[2];
int val, tsize, weight, ran;
void update() {
tsize = son[0]->tsize + son[1]->tsize + weight;
}
}tree[maxN*6],*roots[maxN],*firstNode = tree;
void addEdge(int x, int y, int z) {
w[++total] = z;
son[total] = y;
nxt[total] = e[x];
e[x] = total;
}
void rotate(node* &root, int direction) {
node* tmp = root->son[direction];
root->son[direction] = tmp->son[direction ^ 1];
tmp->son[direction ^ 1] = root;
tmp->tsize = root->tsize;
root->update();
root = tmp;
}
void Insert(node* &root, int val, int num) {
if (root == firstNode) {
++total;
root = &tree[total];
root->tsize = root->weight = num;
root->val = val;
root->ran = rand();
root->son[1] = root->son[0] = firstNode;
return;
}
int d;
if(root->val > val)
d = 0;
else if(root->val < val)
d = 1;
else
d = -1;
root->tsize += num;
if (d == -1)
root->weight += num;
else {
Insert(root->son[d], val, num);
if (root->son[d]->ran < root->ran) {
rotate(root, d);
}
}
}
int Query(node* root, int val) {
if (root == firstNode) return 0;
int d;
if(root->val > val)
d = 0;
else if(root->val < val)
d = 1;
else
d = -1;
if (d < 0)
return root->son[0]->tsize + root->weight;
else if (d)
return root->son[0]->tsize + root->weight + Query(root->son[1], val);
return Query(root->son[0], val);
}
void Join(node* &t1, node*t2) {
if (t2 == firstNode)
return;
Insert(t1, t2->val, t2->weight);
Join(t1, t2->son[0]);
Join(t1, t2->son[1]);
}
int cal(node* t1, node*t2, int val) {
if (t2 == firstNode)
return 0;
return t2->weight*Query(t1, val - t2->val) + cal(t1, t2->son[0],val) + cal(t1, t2->son[1],val);
}
void work(int x, int dep, int fa) {
for (int j = e[x]; j; j = nxt[j]) {
if (son[j] != fa) {
work(son[j], dep + w[j], x);
if (roots[x]->tsize < roots[son[j]]->tsize)
swap(roots[x], roots[son[j]]);
answer += cal(roots[x], roots[son[j]], 2 * dep + m);
Join(roots[x], roots[son[j]]);
}
}
answer += Query(roots[x], dep + m);
Insert(roots[x], dep, 1);
}
int main() {
while (true) {
scanf("%d%d", &n, &m);
if (n == 0)
break;
memset(e, 0, sizeof(e));
memset(son, 0, sizeof(son));
total = 0;
for (int i = 1; i <= n; i++)
roots[i] = firstNode;
int x, y, z;
for (int i = 1; i < n; i++) {
scanf("%d%d%d", &x, &y, &z);
addEdge(x, y, z);
addEdge(y, x, z);
}
total = answer = 0;
work(1, 0, 0);
printf("%d\n", answer);
}
return 0;
}