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abstract class Tree {
private int value;
private Color color;
private int depth;
public Tree(int value, Color color, int depth) {
this.value = value;
this.color = color;
this.depth = depth;
}
public int getValue() {
return value;
}
public Color getColor() {
return color;
}
public int getDepth() {
return depth;
}
public abstract void accept(TreeVis visitor);
}
class TreeNode extends Tree {
private final List children = new ArrayList<>();
public TreeNode(int value, Color color, int depth) {
super(value, color, depth);
}
public void accept(TreeVis visitor) {
visitor.visitNode(this);
for (Tree child : children) {
child.accept(visitor);
}
}
public void addChild(Tree child) {
children.add(child);
}
}
class TreeLeaf extends Tree {
public TreeLeaf(int value, Color color, int depth) {
super(value, color, depth);
}
public void accept(TreeVis visitor) {
visitor.visitLeaf(this);
}
}
abstract class TreeVis {
public abstract int getResult();
public abstract void visitNode(TreeNode node);
public abstract void visitLeaf(TreeLeaf leaf);
}
// Visitor 1: Sum of all leaf values
class SumInLeavesVisitor extends TreeVis {
private int sum = 0;
public int getResult() {
return sum;
}
public void visitNode(TreeNode node) {}
public void visitLeaf(TreeLeaf leaf) {
sum += leaf.getValue();
}
}
// Visitor 2: Product of red node values
class ProductOfRedNodesVisitor extends TreeVis {
private long product = 1;
private final int MOD = 1_000_000_007;
public int getResult() {
return (int) product;
}
public void visitNode(TreeNode node) {
if (node.getColor() == Color.RED) {
product = (product * node.getValue()) % MOD;
}
}
public void visitLeaf(TreeLeaf leaf) {
if (leaf.getColor() == Color.RED) {
product = (product * leaf.getValue()) % MOD;
}
}
}
// Visitor 3: Difference between even depth node sum and green leaf sum
class FancyVisitor extends TreeVis {
private int sumEvenDepthNonLeaf = 0;
private int sumGreenLeaf = 0;
public int getResult() {
return Math.abs(sumEvenDepthNonLeaf - sumGreenLeaf);
}
public void visitNode(TreeNode node) {
if (node.getDepth() % 2 == 0) {
sumEvenDepthNonLeaf += node.getValue();
}
}
public void visitLeaf(TreeLeaf leaf) {
if (leaf.getColor() == Color.GREEN) {
sumGreenLeaf += leaf.getValue();
}
}
}
public class Solution {
private static int[] values;
private static Color[] colors;
private static Map<Integer, List<Integer>> treeMap = new HashMap<>();
public static void main(String[] args) {
Tree root = solve();
TreeVis vis1 = new SumInLeavesVisitor();
TreeVis vis2 = new ProductOfRedNodesVisitor();
TreeVis vis3 = new FancyVisitor();
root.accept(vis1);
root.accept(vis2);
root.accept(vis3);
System.out.println(vis1.getResult());
System.out.println(vis2.getResult());
System.out.println(vis3.getResult());
}
public static Tree solve() {
Scanner sc = new Scanner(System.in);
int n = sc.nextInt();
values = new int[n];
for (int i = 0; i < n; i++) {
values[i] = sc.nextInt();
}
colors = new Color[n];
for (int i = 0; i < n; i++) {
colors[i] = sc.nextInt() == 0 ? Color.RED : Color.GREEN;
}
for (int i = 0; i < n - 1; i++) {
int u = sc.nextInt() - 1;
int v = sc.nextInt() - 1;
treeMap.computeIfAbsent(u, x -> new ArrayList<>()).add(v);
treeMap.computeIfAbsent(v, x -> new ArrayList<>()).add(u);
}
return buildTree(0, 0, -1);
}
private static Tree buildTree(int node, int depth, int parent) {
List<Integer> children = treeMap.getOrDefault(node, new ArrayList<>());
children.remove((Integer) parent);
if (children.isEmpty()) {
return new TreeLeaf(values[node], colors[node], depth);
} else {
TreeNode treeNode = new TreeNode(values[node], colors[node], depth);
for (int child : children) {
treeNode.addChild(buildTree(child, depth + 1, node));
}
return treeNode;
}
}
}
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Java Visitor Pattern
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import java.io.; import java.util.;
enum Color { RED, GREEN }
abstract class Tree { private int value; private Color color; private int depth;
}
class TreeNode extends Tree { private final List children = new ArrayList<>();
}
class TreeLeaf extends Tree { public TreeLeaf(int value, Color color, int depth) { super(value, color, depth); }
}
abstract class TreeVis { public abstract int getResult(); public abstract void visitNode(TreeNode node); public abstract void visitLeaf(TreeLeaf leaf); }
// Visitor 1: Sum of all leaf values class SumInLeavesVisitor extends TreeVis { private int sum = 0;
}
// Visitor 2: Product of red node values class ProductOfRedNodesVisitor extends TreeVis { private long product = 1; private final int MOD = 1_000_000_007;
}
// Visitor 3: Difference between even depth node sum and green leaf sum class FancyVisitor extends TreeVis { private int sumEvenDepthNonLeaf = 0; private int sumGreenLeaf = 0;
}
public class Solution {
}