struct Node{
	Node * left;
	Node * right;
	int lmaxlen;
	int rmaxlen;
	char val;
};

int maxlen = 0;

//查找二叉树中最远的两个节点
void search(Node * root){
	if(root == NULL){
		return ;
	}
	if(root->left != NULL){
		search(root->left);
	}else{
		root->lmaxlen = 0;
	}
	if(root->right != NULL){
		search(root->right);
	}else{
		root->rmaxnlen = 0;
	}
	if(root->left != NULL){
		int tpmaxlen = 0;
		if(root->left->lmaxlen > root->left->rmaxlen){
			tpmaxlen = root->left->lmaxlen;
		}else{
			tpmaxlen = root->left->raxlen;
		}
		root->lmaxlen = tpmaxlen + 1;
	}
	if(root->right != NULL{
		int tpmaxlen = 0;
		if(root->right->rmaxlen > root->right->lmaxlen){
			tpmaxlen = root->right->rmaxlen;	
		}else{
			tpmaxlen = root->right->lmaxlen;
		}
		root->lmaxlen = tpmaxlen + 1;
	}
	if(root->lmaxlen + root->rmaxlen > maxlen){
		maxlen = root->lmaxlen + root->rmaxlen;
	}	
}