4-08：判断子树

问题：判断子树

给定两颗二叉树A，B，判断A是否是B的子结构。

bool issubtree(TreeNode* bigtree, TreeNode* smalltree)
{
	if (smalltree == NULL)
		return true;
	if (bigtree == NULL)
		return false;
	if (bigtree->getvalue() == smalltree->getvalue())
		return issubtree(bigtree->getleft(), smalltree->getleft()) && issubtree(bigtree->getright(), smalltree->getright());
	else
		return false;
}

bool findsubtree(TreeNode* bigtree,TreeNode* smalltree)
{
	if (bigtree == NULL || smalltree == NULL)
		return false;
	bool result = false;
	if (bigtree->getvalue() == smalltree->getvalue())
		result = issubtree(bigtree, smalltree);
	if (!result)
		result = findsubtree(bigtree->getleft(), smalltree);
	if (!result)
		result = findsubtree(bigtree->getright(), smalltree);
	return result;
}