面试题：树的子结构

public class Solution {
    public boolean HasSubtree(TreeNode root1,TreeNode root2) {
        boolean result=false;
        if(root1!=null&&root2!=null){
            if(root1.val==root2.val)
                result=doesTree1Tree2(root1,root2);
            if(!result) {result=HasSubtree(root1.left,root2);}
            if(!result) {result=HasSubtree(root1.right,root2);}
        }
        return result;
    }
    public boolean doesTree1Tree2(TreeNode root1,TreeNode root2) {
        if(root1==null&&root2!=null) return false;
        if(root2==null) return true;
        if(root1.val!=root2.val) return false;
        return doesTree1Tree2(root1.left,root2.left)&&doesTree1Tree2(root1.right,root2.right);
    }
}