1 files changed, 70 insertions, 0 deletions
diff --git a/2019/December/Gold/milkvisits.cpp b/2019/December/Gold/milkvisits.cpp
new file mode 100644
index 0000000..d02c1bc
--- /dev/null
+++ b/2019/December/Gold/milkvisits.cpp
@@ -0,0 +1,70 @@
+#include <bits/stdc++.h>
+#define f first
+#define s second
+using namespace std;
+typedef pair<int, int> ii;
+
+int N, M, T[100001], d[100001] = { 0 }, L[100001][20];
+vector<int> G[100001];
+bitset<100001> ans;
+pair<ii, int> q[100001];
+unordered_set<int> x[100001], y[100001];
+
+void dfs(int u, int p) {
+	d[u] = d[p] + 1;
+	L[u][0] = p;
+	for (int i = 0; i < 18 && L[u][i]; i++) L[u][i + 1] = L[L[u][i]][i];
+	for (auto& v : G[u]) if (v != p) dfs(v, u);
+}
+
+int lca(int u, int v) {
+	if (d[u] > d[v]) swap(u, v);
+	for (int i = 18; i >= 0; i--) if (d[v] - (1 << i) >= d[u]) v = L[v][i];
+	if (u == v) return u;
+	for (int i = 18; i >= 0; i--) if (L[u][i] && L[u][i] != L[v][i]) u = L[u][i], v = L[v][i];
+	return L[u][0];
+}
+
+void solve(int u, int p, unordered_map<int, unordered_set<int>>& S) {
+	for (auto& v : G[u]) {
+		if (v != p) {
+			unordered_map<int, unordered_set<int>> tmp;
+			solve(v, u, tmp);
+			if (tmp.size() > S.size()) swap(tmp, S);
+			for (auto& x : tmp) {
+				for (auto& i : x.s) S[x.f].insert(i);
+			}
+		}
+	}
+	for (auto& i : x[u]) S[q[i].s].insert(i);
+	for (auto& i : S[T[u]]) ans[i] = 1;
+	S[T[u]].clear();
+	for (auto& i : y[u]) {
+		if (S[q[i].s].find(i) != S[q[i].s].end()) S[q[i].s].erase(i);
+	}
+}
+
+int main() {
+	ifstream cin("milkvisits.in");
+	ofstream cout("milkvisits.out");
+	
+	cin >> N >> M;
+	for (int i = 1; i <= N; i++) cin >> T[i];
+	for (int i = 1; i < N; i++) {
+		int u, v;
+		cin >> u >> v;
+		G[u].push_back(v), G[v].push_back(u);
+	}
+	dfs(1, 0);
+	for (int i = 0; i < M; i++) {
+		int a, b, c;
+		cin >> a >> b >> c;
+		q[i] = { ii(a, b), c };
+		int l = lca(a, b);
+		if (a != l) x[a].insert(i), y[l].insert(i);
+		if (b != l) x[b].insert(i), y[l].insert(i);
+	}
+	unordered_map<int, unordered_set<int>> S;
+	solve(1, 0, S);
+	for (int i = 0; i < M; i++) cout << (ans[i] || T[q[i].f.f] == q[i].s || T[q[i].f.s] == q[i].s);
+}