Create find-leaves-of-binary-tree.java

Author: maiquynhtruong

find-leaves-of-binary-tree.java

@@ -0,0 +1,51 @@
+/* package whatever; // don't place package name! */
+
+import java.util.*;
+import java.lang.*;
+import java.io.*;
+
+/* Name of the class has to be "Main" only if the class is public. */
+class Ideone
+{
+	static class TreeNode {
+		int val;
+		TreeNode left = null, right = null;
+		TreeNode(int value) {this.val = value;}
+	}
+	public static void main (String[] args) throws java.lang.Exception
+	{
+		TreeNode root = new TreeNode(0);
+		root.left = new TreeNode(2);
+		root.right = new TreeNode(3);
+		root.left.left = new TreeNode(4);
+		root.left.right = new TreeNode(5);
+		while (root != null) {
+			// more preferred way to create a stack
+			Deque<Integer> stack = new ArrayDeque<Integer>();
+			helper(root, root.left, stack);
+			helper(root, root.right, stack);
+			if (stack.isEmpty()) {
+				stack.addFirst(root.val);
+				System.out.println(Arrays.toString(stack.toArray()));
+				root = null;
+			} else {
+				System.out.println(Arrays.toString(stack.toArray()));
+			}
+			
+		}
+	}
+	
+	public static void helper(TreeNode rootOfRoot,TreeNode root, Deque<Integer> stack) {
+		if (root == null) return;
+		else if (root.left == null && root.right == null) {
+			System.out.println("root.val= " + root.val);
+			stack.addFirst(root.val);
+			if (root == rootOfRoot.left) rootOfRoot.left = null;
+			else rootOfRoot.right = null;
+			return;
+		} else {
+			helper(root, root.left, stack);
+			helper(root, root.right, stack);
+		}
+	}
+}