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Copy pathADABERRY.cpp
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109 lines (109 loc) · 3.05 KB
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// Ivan Carvalho
// Solution to https://www.spoj.com/problems/ADABERRY/
#include <algorithm>
#include <cstdio>
#include <vector>
#define LSOne(S) (S & (-S))
using namespace std;
const int MAXN = 2 * 1e5 + 10;
const int MAX2N = 4 * 1e5 + 20;
const int lo = 0;
const int hi = 1e6;
vector<int> grafo[MAXN], esq[MAX2N], dir[MAX2N], val[MAX2N];
int vetor[MAX2N], numero[MAXN], ini[MAXN], fim[MAXN], dfsNum, segIt[MAX2N], n,
m;
void dfs(int x, int p) {
ini[x] = ++dfsNum;
vetor[dfsNum] = numero[x];
for (int i = 0; i < grafo[x].size(); i++) {
int v = grafo[x][i];
if (v == p) continue;
dfs(v, x);
}
fim[x] = ++dfsNum;
vetor[dfsNum] = numero[x];
}
void update_sparse(int id, int pos, int left, int right, int x) {
val[id][pos]++;
if (left == right) return;
int mid = (left + right) / 2;
if (x <= mid) {
if (esq[id][pos] == -1) {
segIt[id]++;
esq[id].push_back(-1);
dir[id].push_back(-1);
val[id].push_back(0);
esq[id][pos] = segIt[id];
}
update_sparse(id, esq[id][pos], left, mid, x);
} else {
if (dir[id][pos] == -1) {
segIt[id]++;
esq[id].push_back(-1);
dir[id].push_back(-1);
val[id].push_back(0);
dir[id][pos] = segIt[id];
}
update_sparse(id, dir[id][pos], mid + 1, right, x);
}
}
int query_sparse(int id, int pos, int left, int right, int i, int j) {
if (left > right || left > j || right < i) return 0;
if (left >= i && right <= j) {
return val[id][pos];
}
int mid = (left + right) / 2;
int sinistra = (esq[id][pos] == -1)
? 0
: query_sparse(id, esq[id][pos], left, mid, i, j);
int destra = (dir[id][pos] == -1)
? 0
: query_sparse(id, dir[id][pos], mid + 1, right, i, j);
return sinistra + destra;
}
void update_bit(int posx, int posy) {
while (posx <= dfsNum) {
update_sparse(posx, 0, lo, hi, posy);
posx += LSOne(posx);
}
}
int read_bit(int posx, int posy) {
int ans = 0;
while (posx > 0) {
ans += query_sparse(posx, 0, lo, hi, lo, posy);
posx -= LSOne(posx);
}
return ans;
}
int query_bit(int a, int b, int c) {
return read_bit(b, c) - read_bit(a - 1, c);
}
int main() {
scanf("%d %d", &n, &m);
for (int i = 0; i < n; i++) scanf("%d", &numero[i]);
for (int i = 1; i < n; i++) {
int u, v;
scanf("%d %d", &u, &v);
grafo[u].push_back(v);
grafo[v].push_back(u);
}
dfs(0, 0);
// printf("DFS\n");
for (int i = 0; i <= dfsNum + 1; i++) {
val[i].push_back(0);
dir[i].push_back(-1);
esq[i].push_back(-1);
}
// printf("Foi\n");
for (int i = 1; i <= dfsNum; i++) {
update_bit(i, vetor[i]);
}
while (m--) {
int a, b;
scanf("%d %d", &a, &b);
printf("%d\n", query_bit(ini[a], fim[a], b) / 2);
update_bit(ini[a], b);
update_bit(fim[a], b);
}
return 0;
}