#include <iostream>
#include <vector>
#include <stack>
using namespace std;
#define MAXN 200005
#define MAXR 25005
#define INF (long long)1e18
#define BLOCK 450
int n, r, q;
vector<int> homereg(MAXN);
vector<vector<int>> adj(MAXN);
int timer = 1;
int tin[MAXN], tout[MAXN];
vector<vector<int>> sorted(MAXR); // sorted[r] stores the nodes from region r in sorted order of {tin, tout}
vector<int> ind(MAXR);
vector<vector<int>> par(BLOCK, vector<int>(MAXR));
vector<vector<int>> child(BLOCK, vector<int>(MAXR));
vector<int> largeRegions;
void euler(int curr) {
// cout << "curr: " << curr << endl;
tin[curr] = timer++;
sorted[homereg[curr]].push_back(curr);
for(auto next : adj[curr]) {
euler(next);
}
tout[curr] = timer - 1;
}
bool isAnc(int a, int b) {
return tin[a] <= tin[b] && tout[b] <= tout[a];
}
// Get answer for (a, b), sz[a] > BLOCK, sz[b] <= BLOCK
void genPar(int curr, int originalReg, int cnt) {
par[ind[originalReg]][homereg[curr]] += cnt;
int newCount = cnt + (homereg[curr] == originalReg);
for(auto child : adj[curr]) {
genPar(child, originalReg, newCount);
}
}
// Get answer for (a, b), sz[a] <= BLOCK, sz[b] > BLOCK
int genChild(int curr, int originalReg) {
int sub = (homereg[curr] == originalReg);
for(auto child : adj[curr]) {
sub += genChild(child, originalReg);
}
child[ind[originalReg]][homereg[curr]] += sub;
return sub;
}
// Get answer for (a, b), sz[a], sz[b] <= BLOCK
int getAns(int a, int b) {
int l = 0;
int r = 0;
int ans = 0;
stack<int> anc;
while (l < sorted[a].size() || r < sorted[b].size()) {
// cout << "l, r: " << l << " " << r << endl;
if (l < sorted[a].size() && (r == sorted[b].size() || tin[sorted[a][l]] < tin[sorted[b][r]])) {
// cout << "a" << endl;
while (!anc.empty() && !isAnc(anc.top(), sorted[a][l])) {
anc.pop();
}
anc.push(sorted[a][l]);
++l;
}
else {
// cout << "b" << endl;
while (!anc.empty() && !isAnc(anc.top(), sorted[b][r])) {
anc.pop();
}
ans += anc.size();
r++;
}
}
return ans;
}
int main() {
cin >> n >> r >> q >> homereg[1]; // homereg[i] = employee i's home region
for(int i = 2; i <= n; ++i) {
int a;
cin >> a >> homereg[i];
adj[a].push_back(i);
}
euler(1);
// for(int i = 1; i <= n; ++i) {
// cout << i << ": " << tin[i] << " " << tout[i] << endl;
// }
int cnt = 0;
int idx = 0;
for(int i = 1; i <= r; ++i) {
if(sorted[i].size() > BLOCK) {
largeRegions.push_back(i);
ind[i] = idx;
++idx;
}
}
for(auto region : largeRegions) {
genPar(1, region, 0);
genChild(1, region);
}
for(int i = 0; i < q; ++i) {
int a, b;
cin >> a >> b;
if (sorted[a].size() <= BLOCK && sorted[b].size() <= BLOCK) { // brute force because lower than bounds
cout << getAns(a, b) << endl;
// cout << "hello" << endl;
continue;
}
if (sorted[a].size() > BLOCK) {
cout << par[ind[a]][b] << endl;
}
else {
cout << child[ind[b]][a] << endl;
}
}
}
Compilation message
regions.cpp: In function 'int getAns(int, int)':
regions.cpp:67:14: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
67 | while (l < sorted[a].size() || r < sorted[b].size()) {
| ~~^~~~~~~~~~~~~~~~~~
regions.cpp:67:38: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
67 | while (l < sorted[a].size() || r < sorted[b].size()) {
| ~~^~~~~~~~~~~~~~~~~~
regions.cpp:69:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
69 | if (l < sorted[a].size() && (r == sorted[b].size() || tin[sorted[a][l]] < tin[sorted[b][r]])) {
| ~~^~~~~~~~~~~~~~~~~~
regions.cpp:69:40: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
69 | if (l < sorted[a].size() && (r == sorted[b].size() || tin[sorted[a][l]] < tin[sorted[b][r]])) {
| ~~^~~~~~~~~~~~~~~~~~~
regions.cpp: In function 'int main()':
regions.cpp:105:9: warning: unused variable 'cnt' [-Wunused-variable]
105 | int cnt = 0;
| ^~~
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
41 ms |
94672 KB |
Output is correct |
| 2 |
Correct |
44 ms |
94612 KB |
Output is correct |
| 3 |
Correct |
45 ms |
94608 KB |
Output is correct |
| 4 |
Correct |
51 ms |
94656 KB |
Output is correct |
| 5 |
Correct |
51 ms |
94552 KB |
Output is correct |
| 6 |
Correct |
63 ms |
94724 KB |
Output is correct |
| 7 |
Correct |
61 ms |
94712 KB |
Output is correct |
| 8 |
Correct |
84 ms |
94720 KB |
Output is correct |
| 9 |
Correct |
104 ms |
95156 KB |
Output is correct |
| 10 |
Correct |
131 ms |
95104 KB |
Output is correct |
| 11 |
Correct |
182 ms |
95336 KB |
Output is correct |
| 12 |
Correct |
168 ms |
95792 KB |
Output is correct |
| 13 |
Correct |
165 ms |
95412 KB |
Output is correct |
| 14 |
Correct |
306 ms |
95956 KB |
Output is correct |
| 15 |
Correct |
328 ms |
98376 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
1006 ms |
98604 KB |
Output is correct |
| 2 |
Correct |
1296 ms |
97400 KB |
Output is correct |
| 3 |
Correct |
2145 ms |
100288 KB |
Output is correct |
| 4 |
Correct |
330 ms |
96064 KB |
Output is correct |
| 5 |
Correct |
503 ms |
97532 KB |
Output is correct |
| 6 |
Correct |
726 ms |
97016 KB |
Output is correct |
| 7 |
Correct |
1461 ms |
97856 KB |
Output is correct |
| 8 |
Correct |
1157 ms |
102488 KB |
Output is correct |
| 9 |
Correct |
2198 ms |
102284 KB |
Output is correct |
| 10 |
Correct |
2767 ms |
106904 KB |
Output is correct |
| 11 |
Correct |
3523 ms |
101596 KB |
Output is correct |
| 12 |
Correct |
1210 ms |
103376 KB |
Output is correct |
| 13 |
Correct |
1896 ms |
103572 KB |
Output is correct |
| 14 |
Correct |
2917 ms |
103188 KB |
Output is correct |
| 15 |
Correct |
2764 ms |
107404 KB |
Output is correct |
| 16 |
Correct |
3409 ms |
112832 KB |
Output is correct |
| 17 |
Correct |
2817 ms |
111640 KB |
Output is correct |
