#include <bits/stdc++.h>
using namespace std;
#define fast ios::sync_with_stdio(0);cin.tie(0);
#define s second
#define f first
typedef long long ll;
const ll MOD = 1e9 + 9;
const ll LOGN = 21;
const ll MAXN = 2e5 + 100;
vector<vector<int>> graph;
int reg[MAXN], dp[505][505];
vector<int> cnt[MAXN], Rin[25100], Rout[25100], plc[25100];
map<pair<int,int>, pair<int,bool>> memo;
void dfs(int node, int parent) {
cnt[node][reg[node]]++;
for (int reg_other = 1; reg_other <= 500; reg_other++)
dp[reg_other][reg[node]] += cnt[node][reg_other];
for (auto u : graph[node]) {
swap(cnt[u], cnt[node]);
dfs(u, node);
}
cnt[node][reg[node]]--;
swap(cnt[parent], cnt[node]);
}
int T = 0;
int tin[MAXN], tout[MAXN];
void dfs2(int node, int parent) {
tin[node] = ++T;
Rin[reg[node]].push_back(tin[node]);
for (auto u : graph[node])
dfs2(u, node);
tout[node] = ++T;
Rout[reg[node]].push_back(tin[node]);
}
int main() {
fast
int N, R, Q, a, b;
cin >> N >> R >> Q;
graph = vector<vector<int>>(N+1, vector<int>());
cin >> reg[1];
plc[reg[1]].push_back(1);
for (int i = 2; i <= N; i++) {
int S;
cin >> S >> reg[i];
plc[reg[i]].push_back(i);
graph[S].push_back(i);
}
if (R <= 500) {
cnt[1] = vector<int>(505, 0);
dfs(1, 1);
for (int i = 0; i < Q; i++) {
cin >> a >> b;
cout << dp[a][b] << endl;
}
} else {
dfs2(1, 1);
for (int i = 1; i <= R; i++) {
sort(Rin[i].begin(), Rin[i].end());
sort(Rend[i].begin(), Rend[i].end());
}
for (int i = 0; i < Q; i++) {
cin >> a >> b;
if (memo[{a, b}].s == false) {
int ans = 0;
if (plc[a].size() < plc[b].size())
for (auto u : plc[a])
ans += (upper_bound(Rin[b].begin(), Rin[b].end(), tout[u]) - Rin[b].begin()) - (upper_bound(Rin[b].begin(), Rin[b].end(), tin[u]) - Rin[b].begin());
else
for (auto u : plc[b])
ans += (upper_bound(Rin[a].begin(), Rin[a].end(), tin[u]) - Rin[a].begin()) - (upper_bound(Rout[a].begin(), Rout[a].end(), tin[u]) - Rout[a].begin());
memo[{a, b}] = {ans, 1};
}
cout << memo[{a, b}].f << endl;
}
}
}
Compilation message
regions.cpp: In function 'int main()':
regions.cpp:66:9: error: 'Rend' was not declared in this scope
66 | sort(Rend[i].begin(), Rend[i].end());
| ^~~~
