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tree_divide2.cpp
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#include <cstdio>
#include <vector>
#include <cstring>
#include <algorithm>
using std::pair;
using std::make_pair;
const int N = 100010;
const int M = 200010;
struct Node* null;
struct Node
{
Node* c[2];
Node* fa;
int val, depth, mx;
int id;
int mi_id;
inline void setc(int d, Node *s) {
c[d] = s;
s->fa = this;
}
inline bool d() {
return fa->c[1] == this;
}
void up() {
mx = val; mi_id = id;
if(c[0]->mx > mx || c[0]->mx == mx && c[0]->mi_id < mi_id) {
mx = c[0]->mx;
mi_id = c[0]->mi_id;
}
if(c[1]->mx > mx || c[1]->mx == mx && c[1]->mi_id < mi_id) {
mx = c[1]->mx;
mi_id = c[1]->mi_id;
}
}
void clear() {
c[0] = c[1] = fa = null;
}
}node[N * 40], *pool;
struct SplayTree
{
Node* root;
void rot(Node* x)
{
Node* p = x->fa;
int f = x->d();
p->fa->setc(p->d(), x);
p->setc(f, x->c[!f]);
x->setc(!f, p);
p->up();
}
void splay(Node* x, Node* goal)
{
while(x->fa != goal) {
if(x->fa->fa == goal) {
rot(x);
} else {
x->d() == (x->fa->d()) ? rot(x->fa): rot(x);
rot(x);
}
}
x->up();
if(goal == null) {
root = x;
}
}
void insert(int depth, int value, int ind)
{
if(root == null) {
Node* tmp = pool++;
tmp->clear();
tmp->val = value;
tmp->id = ind;
tmp->mi_id = ind;
tmp->depth = depth;
tmp->mx = value;
root = tmp;
return ;
}
Node* x = root;
Node* p = null;
int c = -1;
while(x != null) {
p = x;
if(x->depth == depth) {
break;
}
if(x->depth < depth) {
x = x->c[1];
c = 1;
} else {
x = x->c[0];
c = 0;
}
}
if(x != null) {
splay(x, null);
if(value > x->val || value == x->val && ind < x->id) {
x->id = ind;
x->val = value;
x->up();
}
return ;
}
Node* tmp = pool++;
tmp->clear();
tmp->val = value;
tmp->id = ind;
tmp->depth = depth;
p->setc(c, tmp);
splay(tmp, null);
}
pair<int, int> query(int d)
{
int ret = -1, mx = -1;
Node* x = root;
Node* p = null;
while(x != null) {
p = x;
if(x->depth <= d) {
if(x->c[0]->mx > mx || x->c[0]->mx == mx && x->c[0]->mi_id < ret) {
mx = x->c[0]->mx;
ret = x->c[0]->mi_id;
}
if(x->val > mx || x->val == mx && x->id < ret) {
mx = x->val;
ret = x->id;
}
x = x->c[1];
} else {
x = x->c[0];
}
}
if(p != null)
splay(p, null);
return make_pair(ret, mx);
}
void init()
{
root = null;
}
}spt[N * 40];
int spt_size;
struct Center
{
int d;
SplayTree* root;
Center(int d, SplayTree* root): d(d), root(root) {
}
};
std::vector<Center> edge[N];
int first[N], pnt[M], nxt[M], weight[M], E, mx[N], w[N], n, solved[N], queue[N], parent[N], depth[N], size[N];
void init(int n)
{
E = 0;
std::fill(first, first + n + 1, -1);
std::fill(solved, solved + n + 1, 0);
pool = node;
spt_size = 0;
for(int i = 1; i <= n; i++) {
edge[i].clear();
}
}
void add_edge(int a, int b, int c)
{
pnt[E] = b;
nxt[E] = first[a];
weight[E] = c;
first[a] = E++;
}
int bfs(int root, int fa)
{
int head = 0, tail = 0;
queue[tail++] = root;
parent[root] = fa;
while(head < tail) {
int u = queue[head++];
for(int i = first[u]; ~i; i = nxt[i]) {
int v = pnt[i];
if(v != parent[u] && !solved[v]) {
queue[tail++] = v;
parent[v] = u;
depth[v] = depth[u] + weight[i];
}
}
}
return tail;
}
int get_root(int root, int &sz)
{
int tail = bfs(root, -1);
for(int i = 0; i < tail; i++) {
int u = queue[i];
size[u] = mx[u] = 1;
}
for(int i = tail - 1; i >= 1; i--) {
int u = queue[i];
size[parent[u]] += size[u];
mx[parent[u]] = std::max(mx[parent[u]], size[u]);
}
for(int i = 0; i < tail; i++) {
int u = queue[i];
mx[u] = std::max(mx[u], tail - size[u]);
if(mx[u] < mx[root]) {
root = u;
}
}
sz = tail;
return root;
}
void solve(int root)
{
int sz = -1;
depth[root] = 0;
root = get_root(root, sz);
solved[root] = 1;
SplayTree *_tree = &spt[spt_size];
edge[root].push_back(Center(0, _tree));
_tree->init();
_tree->insert(0, w[root], root);
spt_size++;
for(int i = first[root]; ~i; i = nxt[i]) {
int v = pnt[i];
if(solved[v]) {
continue;
}
depth[v] = weight[i];
int tail = bfs(v, root);
for(int i = 0; i < tail; i++) {
int u = queue[i];
edge[u].push_back(Center(depth[u], _tree));
_tree->insert(depth[u], w[u], u);
}
solve(v);
}
}
int get_val(){
int ret(0),sign(1);
char c;
while((c=getchar())==' '||c=='\n'||c=='\r');if(c=='-') sign=-1;
else ret=c-'0';
while((c=getchar())!=' '&&c!='\n'&&c!='\r') if(c=='-') sign=-1;
else ret=ret*10+c-'0';
return ret*sign;
}
int main()
{
null = new Node();
null->clear();
null->mx = -1;
int q, a, b, c;
while(scanf("%d", &n) == 1) {
init(n);
for(int i = 1; i <= n; i++) {
//scanf("%d", &w[i]);
w[i]=get_val();
}
for(int i = 1; i < n; i++) {
a=get_val(),b=get_val(),c=get_val();
//scanf("%d%d%d", &a, &b, &c);
add_edge(a, b, c);
add_edge(b, a, c);
}
solve(1);
scanf("%d", &q);
while(q--) {
//scanf("%d%d", &a, &b);
a=get_val(),b=get_val();
int ret = 0, mx = 0;
for(int i = 0; i < (int)edge[a].size(); i++) {
Center root = edge[a][i];
if(b >= root.d) {
pair<int, int> tmp = root.root->query(b - root.d);
if(tmp.second > mx || tmp.second == mx && tmp.first < ret) {
ret = tmp.first;
mx = tmp.second;
}
}
}
printf("%d\n", ret);
}
}
return 0;
}