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#include "../util.h"
vector<vector<int>> adj;
#include <graph/centroid.cpp>
int subtreeSize(int c, int p) {
int res = 1;
for (int x : adj[c]) {
if (x == p) continue;
res += subtreeSize(x, c);
}
return res;
}
vector<int> naive() {
vector<int> res;
for (int i = 0; i < ssize(adj); i++) {
bool isCentroid = true;
for (int j : adj[i]) isCentroid &= 2*subtreeSize(j, i) <= ssize(adj);
if (isCentroid) res.push_back(i);
}
return res;
}
void stress_test() {
ll queries = 0;
for (int tries = 0; tries < 100'000; tries++) {
int n = Random::integer<int>(1, 50);
Graph<NoData> g(n);
g.tree();
adj.assign(n, {});
g.forEdges([&](int a, int b){
adj[a].push_back(b);
adj[b].push_back(a);
});
auto expected = naive();
ranges::sort(expected);
for (int i = 0; i < n; i++) {
auto [a, b] = find_centroid(i);
vector<int> got;
if (a >= 0) got.push_back(a);
if (b >= 0) got.push_back(b);
ranges::sort(got);
if (got != expected) cerr << "error" << FAIL;
}
queries += n;
}
cerr << "tested random queries: " << queries << endl;
}
constexpr int N = 2'000'000;
void performance_test() {
timer t;
Graph<NoData> g(N);
g.tree();
adj.assign(N, {});
g.forEdges([&](int a, int b){
adj[a].push_back(b);
adj[b].push_back(a);
});
t.start();
auto [gotA, gotB] = find_centroid();
t.stop();
hash_t hash = gotA + gotB;
if (t.time > 500) cerr << "too slow: " << t.time << FAIL;
cerr << "tested performance: " << t.time << "ms (hash: " << hash << ")" << endl;
}
int main() {
stress_test();
performance_test();
}
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