Java Exercises: Test if a binary tree is a subtree of another binary tree

Java Basic: Exercise-150 with Solution

Write a Java program to test if a binary tree is a subtree of another binary tree.

Sample Solution:

Java Code:

public  class  Solution {
	  /**
     * @param T1, T2: The roots of binary tree.
     * @return: True if T2 is a subtree of T1, or false.
     */
        public static boolean is_Subtree(TreeNode T1, TreeNode T2) {
        if (T2 == null) return true;
        if (T1 == null) return false;
        if (is_Same(T1, T2)) return true;
        if (is_Subtree(T1.left, T2) || is_Subtree(T1.right, T2)) return true;
        return false;
    }

    public static boolean is_Same(TreeNode t1, TreeNode t2) {
        if (t1 == null || t2 == null) {
            return t1 == t2;
        } else if (t1.val != t2.val) {
            return false;
        } else {
            return is_Same(t1.left, t2.left) && is_Same(t1.right, t2.right);
        }
    }
   /* Driver program to test above functions */
	public static void main(String[] args) {
        TreeNode t1 = new TreeNode(1);
        TreeNode t2 = new TreeNode(2);
        TreeNode t3 = new TreeNode(3);
        TreeNode t4 = new TreeNode(4);
        t1.left  = t2;
        t1.right = t3;
       
        TreeNode n1 = new TreeNode(1);
        TreeNode n2 = new TreeNode(2);
        TreeNode n3 = new TreeNode(3);
        TreeNode n4 = new TreeNode(4);
        n1.left  = n2;
        n1.right = n3;
      
        System.out.println(is_Subtree(t1, n1));
    }
  }
  class TreeNode {
    public int val;
    public TreeNode left, right;

    public TreeNode(int val) {
        this.val = val;
        this.left = this.right = null;
    }
  }

Sample Output:

true

Flowchart:

Java Code Editor:

Contribute your code and comments through Disqus.

Previous: Write a Java program to check if a given string is a permutation of another given string.
Next: Write a Java program to find the value of specified expression.