树的子结构

public class Solution {
    public boolean HasSubtree(TreeNode T1, TreeNode T2) {
        if (T2 == null || T1==null) {
            return false;
        }

        if (isEqual(T1, T2)) {
            return true;
        }
        if (HasSubtree(T1.left, T2) || HasSubtree(T1.right, T2)) {
            return true;
        }
        return false;
    }

    private boolean isEqual(TreeNode T1, TreeNode T2) {
        if (T2 == null) {
            return true;
        }
        if(T1 == null){
            return false;
        }
        if (T1.val != T2.val) {
            return false;
        }
        return isEqual(T1.left, T2.left) && isEqual(T1.right, T2.right);
    }
}