Subtree

    2.  * Definition of TreeNode:
    3.  * public class TreeNode {
    4.  *     public int val;
    5.  *     public TreeNode(int val) {
    6.  *         this.val = val;
    7.  *         this.left = this.right = null;
    8.  *     }
    9.  * }
    10.  */
    12.     /**
    13.      * @param T1, T2: The roots of binary tree.
    14.      * @return: True if T2 is a subtree of T1, or false.
    15.      */
    16.         if (T2 == null) return true;
    17.         if (T1 == null) return false;
    18.         return identical(T1, T2) || isSubtree(T1.left, T2) || isSubtree(T1.right, T2);
    19.     }
    22.         if (T1 == null && T2 == null) return true;
    23.         if (T1 == null || T2 == null) return false;
    24.         if (T1.val != T2.val) return false;
    25.         return identical(T1.left, T2.left) && identical(T1.right, T2.right);
    26.     }