#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using db = long double;
using str = string;
using pi = pair<int, int>;
using pl = pair<ll, ll>;
using pd = pair<db, db>;
using vi = vector<int>;
using vb = vector<bool>;
using vl = vector<ll>;
using vd = vector<db>;
using vs = vector<str>;
using vpi = vector<pi>;
using vpl = vector<pl>;
using vpd = vector<pd>;
#define mp make_pair
#define f first
#define s second
#define sz(x) (int)(x).size()
#define bg(x) begin(x)
#define all(x) bg(x), end(x)
#define sor(x) sort(all(x))
#define ft front()
#define bk back()
#define pb push_back
#define pf push_front
#define lb lower_bound
#define ub upper_bound
#define FOR(i, a, b) for (int i = (a); i < (b); i++)
#define F0R(i, a) FOR(i, 0, a)
#define ROF(i, a, b) for (int i = (b) - 1; i >= (a); i--)
#define R0F(i, a) ROF(i, 0, a)
#define EACH(a, x) for (auto& a : x)
const int MOD = 1e9 + 7;
const int MXN = 2e5 + 10;
const int MXR = 25010;
const ll INF = 1e18;
const int BLOCK = 450;
int N, R, Q; vi adj[MXN]; int L[MXN]; // L[i] = Region of i
int timer = 1, in[MXN], out[MXN]; vi S[MXR]; // Sorted list of {in, out} for each region
vi large; int child[BLOCK][MXN], par[BLOCK][MXN]; int ind[MXR];
// Preorder Traversal ~ O(N)
void DFS(int X, int P) {
in[X] = timer++; S[L[X]].pb(X);
EACH(Y, adj[X]) if (Y != P) DFS(Y, X); out[X] = timer - 1;
}
bool isAnc(int A, int B) { return in[A] <= in[B] && out[B] <= out[A]; }
// Generate child[][] and par[][] DFS ~ O(N)
int genChild(int X, int P, int reg) {
int sub = (L[X] == reg); EACH(Y, adj[X]) if (Y != P) sub += genChild(Y, X, reg);
child[ind[reg]][L[X]] += sub; return sub;
}
void genPar(int X, int P, int reg, int cnt) {
par[ind[reg]][L[X]] += cnt; cnt += (L[X] == reg);
EACH(Y, adj[X]) if (Y != P) genPar(Y, X, reg, cnt);
}
// Get the answer when queried (A, B) ~ O(N)
int genAns(int A, int B) {
int ans = 0; int L = 0, R = 0; int last = 0; deque<int> anc;
while (L < sz(S[A]) || R < sz(S[B])) {
if (L < sz(S[A]) && (R >= sz(S[B]) || in[S[A][L]] < in[S[B][R]])) {
while (sz(anc) && !isAnc(anc.bk, S[A][L])) anc.pop_back(); anc.pb(S[A][L++]);
}
else { while (sz(anc) && !isAnc(anc.bk, S[B][R])) anc.pop_back(); ans += sz(anc); R++; }
}
return ans;
}
int main() {
ios_base::sync_with_stdio(false); cin.tie(0);
cin >> N >> R >> Q >> L[1];
FOR(i, 2, N + 1) { int A; cin >> A >> L[i]; adj[A].pb(i), adj[i].pb(A); }
DFS(1, 0); int cur = 0; FOR(i, 1, R + 1) if (sz(S[i]) >= BLOCK) large.pb(i), ind[i] = cur++;
EACH(i, large) { genChild(1, 0, i); genPar(1, 0, i, 0); }
F0R(i, Q) {
int A, B; cin >> A>> B;
if (sz(S[A]) >= BLOCK) cout << par[ind[A]][B] << endl;
else if (sz(S[B]) >= BLOCK) cout << child[ind[B]][A] << endl;
else cout << genAns(A, B) << endl;
}
}
Compilation message
regions.cpp: In function 'void DFS(int, int)':
regions.cpp:42:20: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
42 | #define EACH(a, x) for (auto& a : x)
| ^~~
regions.cpp:62:5: note: in expansion of macro 'EACH'
62 | EACH(Y, adj[X]) if (Y != P) DFS(Y, X); out[X] = timer - 1;
| ^~~~
regions.cpp:62:44: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'for'
62 | EACH(Y, adj[X]) if (Y != P) DFS(Y, X); out[X] = timer - 1;
| ^~~
regions.cpp: In function 'int genAns(int, int)':
regions.cpp:86:13: warning: this 'while' clause does not guard... [-Wmisleading-indentation]
86 | while (sz(anc) && !isAnc(anc.bk, S[A][L])) anc.pop_back(); anc.pb(S[A][L++]);
| ^~~~~
regions.cpp:86:72: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'while'
86 | while (sz(anc) && !isAnc(anc.bk, S[A][L])) anc.pop_back(); anc.pb(S[A][L++]);
| ^~~
regions.cpp:82:40: warning: unused variable 'last' [-Wunused-variable]
82 | int ans = 0; int L = 0, R = 0; int last = 0; deque<int> anc;
| ^~~~
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
4 ms |
5576 KB |
Output is correct |
| 2 |
Correct |
5 ms |
5576 KB |
Output is correct |
| 3 |
Correct |
7 ms |
5576 KB |
Output is correct |
| 4 |
Correct |
9 ms |
5576 KB |
Output is correct |
| 5 |
Correct |
14 ms |
5576 KB |
Output is correct |
| 6 |
Correct |
22 ms |
5700 KB |
Output is correct |
| 7 |
Correct |
43 ms |
5704 KB |
Output is correct |
| 8 |
Correct |
31 ms |
5704 KB |
Output is correct |
| 9 |
Correct |
30 ms |
6088 KB |
Output is correct |
| 10 |
Correct |
96 ms |
6088 KB |
Output is correct |
| 11 |
Correct |
144 ms |
6344 KB |
Output is correct |
| 12 |
Correct |
188 ms |
6728 KB |
Output is correct |
| 13 |
Correct |
228 ms |
6856 KB |
Output is correct |
| 14 |
Correct |
284 ms |
7064 KB |
Output is correct |
| 15 |
Correct |
293 ms |
9416 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
1178 ms |
10624 KB |
Output is correct |
| 2 |
Correct |
1579 ms |
9928 KB |
Output is correct |
| 3 |
Correct |
1986 ms |
12852 KB |
Output is correct |
| 4 |
Correct |
367 ms |
7240 KB |
Output is correct |
| 5 |
Correct |
399 ms |
8648 KB |
Output is correct |
| 6 |
Correct |
862 ms |
12532 KB |
Output is correct |
| 7 |
Correct |
1876 ms |
10744 KB |
Output is correct |
| 8 |
Correct |
1387 ms |
24832 KB |
Output is correct |
| 9 |
Correct |
2624 ms |
14144 KB |
Output is correct |
| 10 |
Correct |
3253 ms |
32560 KB |
Output is correct |
| 11 |
Correct |
4766 ms |
16292 KB |
Output is correct |
| 12 |
Correct |
1421 ms |
15620 KB |
Output is correct |
| 13 |
Correct |
2290 ms |
16796 KB |
Output is correct |
| 14 |
Correct |
2738 ms |
20056 KB |
Output is correct |
| 15 |
Correct |
3227 ms |
21764 KB |
Output is correct |
| 16 |
Correct |
3126 ms |
30912 KB |
Output is correct |
| 17 |
Correct |
3290 ms |
32448 KB |
Output is correct |
