feat: initial commit for pat advanced 1004 using Java

AdvancedLevel_Java/1004 Counting Leaves (30).java

@@ -0,0 +1,98 @@
+import java.io.BufferedReader;
+import java.io.InputStreamReader;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Map;
+import java.util.Queue;
+import java.util.Scanner;
+
+public class Main {
+
+    public static void main(String[] args) {
+        try (Scanner scanner = new Scanner(new BufferedReader(new InputStreamReader(System.in)))) {
+            int totalNodes = scanner.nextInt();
+            if (totalNodes == 0) {
+                System.out.println(totalNodes);
+                return;
+            }
+            int nonLeafNodesCount = scanner.nextInt();
+            if (nonLeafNodesCount == 0) {
+                System.out.println(totalNodes);
+                return;
+            }
+            scanner.nextLine();
+            String[] lines = new String[nonLeafNodesCount];
+            for (int i = 0; i < nonLeafNodesCount; i++) {
+                lines[i] = scanner.nextLine();
+            }
+
+            Map<String, Node> tree = new HashMap<>();
+            createTree(tree, lines);
+            List<Integer> leafCounts = countLeafNodes(tree);
+            printList(leafCounts);
+        } catch (NumberFormatException e) {
+            System.err.println("Error parsing input");
+        }
+    }
+
+    private static void createTree(Map<String, Node> tree, String[] lines) {
+        for (String line : lines) {
+            String[] parts = line.split("\\s+");
+            String id = parts[0];
+            Node node = tree.getOrDefault(id, new Node(id));
+            int numChildren = Integer.parseInt(parts[1]);
+            for (int i = 0; i < numChildren; i++) {
+                String childId = parts[i + 2];
+                Node child = tree.getOrDefault(childId, new Node(childId));
+                node.appendChild(child);
+                tree.put(childId, child);
+            }
+            tree.put(id, node);
+        }
+    }
+
+    private static List<Integer> countLeafNodes(Map<String, Node> tree) {
+        List<Integer> counts = new ArrayList<>();
+        Queue<Node> queue = new LinkedList<>();
+        queue.add(tree.get("01"));
+        while (!queue.isEmpty()) {
+            int size = queue.size();
+            int count = 0;
+            for (int i = 0; i < size; i++) {
+                Node current = queue.poll();
+                if (current.children.isEmpty()) {
+                    count++;
+                } else {
+                    queue.addAll(current.children);
+                }
+            }
+            counts.add(count);
+        }
+        return counts;
+    }
+
+    private static void printList(List<Integer> counts) {
+        for (int i = 0; i < counts.size(); i++) {
+            if (i == counts.size() - 1) {
+                System.out.println(counts.get(i));
+            } else {
+                System.out.print(counts.get(i) + " ");
+            }
+        }
+    }
+
+    static class Node {
+        String id;
+        List<Node> children = new ArrayList<>();
+
+        public Node(String id) {
+            this.id = id;
+        }
+
+        public void appendChild(Node node) {
+            this.children.add(node);
+        }
+    }
+}