[itint5]完全二叉树节点个数的统计

//使用getLeftChildNode(TreeNode)获得左儿子结点
//使用getRightChildNode(TreeNode)获得右儿子结点
//使用isNullNode(TreeNode)判断结点是否为空
int get_left_height(TreeNode root) {
if (isNullNode(root)) {
return 0;
} else {
return get_left_height(getLeftChildNode(root)) + 1;
}
}

int count_complete_binary_tree_nodes(TreeNode root) {
if (isNullNode(root))
return 0;
TreeNode leftNode = getLeftChildNode(root);
TreeNode rightNode = getRightChildNode(root);
int lheight = get_left_height(leftNode);
int rheight = get_left_height(rightNode);
if (lheight == rheight) {
return (1 << lheight) + count_complete_binary_tree_nodes(rightNode);
} else {
return (1 << rheight) + count_complete_binary_tree_nodes(leftNode);
}
}