1 files changed, 75 insertions, 0 deletions
diff --git a/18.5/open/plat/boxes.cpp b/18.5/open/plat/boxes.cpp
new file mode 100644
index 0000000..75695b9
--- /dev/null
+++ b/18.5/open/plat/boxes.cpp
@@ -0,0 +1,75 @@
+#include <bits/stdc++.h>
+#include "grader.h"
+using namespace std;
+typedef pair<int, int> ii;
+typedef vector<int> vi;
+typedef vector<ii> vii;
+
+int d[100005], sz[100005], L[100005][20];
+ii P[100005];
+vi G[100005];
+
+void addRoad(int a, int b) {
+	G[a].push_back(b);
+	G[b].push_back(a);
+}
+
+void dfs(int u, int p) {
+	d[u] = (p != -1 ? d[p] : 0) + 1;
+	sz[u] = 1;
+	L[u][0] = p;
+	for (int i = 0; i < 16; i++) {
+		if (L[u][i] != -1) L[u][i + 1] = L[L[u][i]][i];
+	}
+	for (auto& v : G[u]) {
+		if (v != p) {
+			dfs(v, u);
+			sz[u] += sz[v];
+		}
+	}
+}
+
+int lca(int u, int v) {
+	if (d[u] > d[v]) swap(u, v);
+	for (int i = 16; i >= 0; i--) if (d[v] - (1 << i) >= d[u]) v = L[v][i];
+	if (u == v) return u;
+	for (int i = 16; i >= 0; i--) if (L[u][i] != -1 && L[u][i] != L[v][i]) u = L[u][i], v = L[v][i];
+	return L[u][0];
+}
+
+int pre(int l, int u) {
+	for (int i = 16; i >= 0; i--) {
+		if (L[u][i] != -1 && d[L[u][i]] > d[l]) u = L[u][i];
+	}
+	return u;
+}
+
+void solve(int u, int p, int x, int y) {
+	P[u] = ii(x, y);
+	setFarmLocation(u, x, y);
+	y += sz[u];
+	for (auto& v : G[u]) {
+		if (v != p) {
+			y -= sz[v];
+			solve(v, u, x, y);
+			x += sz[v];
+		}
+	}
+}
+
+void buildFarms() {
+	memset(L, -1, sizeof(L));
+	dfs(0, -1);
+	solve(0, -1, 1, 1);
+}
+
+void notifyFJ(int a, int b) {
+	if (a == b) addBox(P[a].first, P[a].second, P[a].first, P[a].second);
+	else {
+		int u = lca(a, b);
+		int v = pre(u, (a != u ? a : b));
+		if (a != u) swap(u, v);
+		addBox(P[u].first, P[u].second, P[a].first, P[a].second);
+		addBox(P[v].first, P[v].second, P[b].first, P[b].second);
+	}
+}