以二叉链表为存储结构，完成以下功能： 以先序递归方式创建一棵二叉树；输出二叉树的先序、中序和后序递归或非递归遍历下的结点访问次序；输出二叉树所有的叶子节点和叶子节点个数；输出二叉树的高度；输出二叉树的按层次遍历序列（提示：实现需用到队列）；

以下是基于C++语言的实现： ```cpp #include <iostream> #include <queue> using namespace std; // 二叉树结点定义 struct TreeNode { int val; TreeNode* left; TreeNode* right; TreeNode(int x) : val(x), left(nullptr), right(nullptr) {} }; // 以先序递归方式创建一棵二叉树 TreeNode* createTree() { int val; cin >> val; if (val == -1) { return nullptr; // -1表示空结点 } TreeNode* root = new TreeNode(val); root->left = createTree(); root->right = createTree(); return root; } // 先序递归遍历二叉树 void preOrderTraversalRecursive(TreeNode* root) { if (!root) { return; } cout << root->val << " "; preOrderTraversalRecursive(root->left); preOrderTraversalRecursive(root->right); } // 中序递归遍历二叉树 void inOrderTraversalRecursive(TreeNode* root) { if (!root) { return; } inOrderTraversalRecursive(root->left); cout << root->val << " "; inOrderTraversalRecursive(root->right); } // 后序递归遍历二叉树 void postOrderTraversalRecursive(TreeNode* root) { if (!root) { return; } postOrderTraversalRecursive(root->left); postOrderTraversalRecursive(root->right); cout << root->val << " "; } // 先序非递归遍历二叉树 void preOrderTraversalNonRecursive(TreeNode* root) { if (!root) { return; } stack<TreeNode*> s; s.push(root); while (!s.empty()) { TreeNode* curr = s.top(); s.pop(); cout << curr->val << " "; if (curr->right) { s.push(curr->right); // 先访问右子树 } if (curr->left) { s.push(curr->left); } } } // 中序非递归遍历二叉树 void inOrderTraversalNonRecursive(TreeNode* root) { if (!root) { return; } stack<TreeNode*> s; TreeNode* curr = root; while (curr || !s.empty()) { while (curr) { s.push(curr); curr = curr->left; // 一直往左走 } curr = s.top(); s.pop(); cout << curr->val << " "; curr = curr->right; // 转向右子树 } } // 后序非递归遍历二叉树 void postOrderTraversalNonRecursive(TreeNode* root) { if (!root) { return; } stack<TreeNode*> s; TreeNode* prev = nullptr; while (root || !s.empty()) { while (root) { s.push(root); root = root->left; } TreeNode* top = s.top(); if (top->right && top->right != prev) { root = top->right; // 左子树遍历完毕，转向右子树 } else { cout << top->val << " "; prev = top; s.pop(); } } } // 输出二叉树所有的叶子节点和叶子节点个数 void printLeaves(TreeNode* root, int& count) { if (!root) { return; } if (!root->left && !root->right) { cout << root->val << " "; count++; } printLeaves(root->left, count); printLeaves(root->right, count); } // 输出二叉树的高度 int getHeight(TreeNode* root) { if (!root) { return 0; } int leftHeight = getHeight(root->left); int rightHeight = getHeight(root->right); return max(leftHeight, rightHeight) + 1; } // 输出二叉树的按层次遍历序列 void levelOrderTraversal(TreeNode* root) { if (!root) { return; } queue<TreeNode*> q; q.push(root); while (!q.empty()) { TreeNode* curr = q.front(); q.pop(); cout << curr->val << " "; if (curr->left) { q.push(curr->left); } if (curr->right) { q.push(curr->right); } } } int main() { TreeNode* root = createTree(); cout << "先序递归遍历："; preOrderTraversalRecursive(root); cout << endl; cout << "中序递归遍历："; inOrderTraversalRecursive(root); cout << endl; cout << "后序递归遍历："; postOrderTraversalRecursive(root); cout << endl; cout << "先序非递归遍历："; preOrderTraversalNonRecursive(root); cout << endl; cout << "中序非递归遍历："; inOrderTraversalNonRecursive(root); cout << endl; cout << "后序非递归遍历："; postOrderTraversalNonRecursive(root); cout << endl; int count = 0; cout << "叶子节点为："; printLeaves(root, count); cout << endl << "叶子节点个数为：" << count << endl; cout << "二叉树的高度为：" << getHeight(root) << endl; cout << "按层次遍历序列为："; levelOrderTraversal(root); cout << endl; return 0; } ``` 输入格式： ``` 1 2 -1 -1 3 4 -1 -1 5 -1 -1 ``` 输出格式： ``` 先序递归遍历：1 2 3 4 5 中序递归遍历：2 1 4 3 5 后序递归遍历：2 4 5 3 1 先序非递归遍历：1 2 3 4 5 中序非递归遍历：2 1 4 3 5 后序非递归遍历：2 4 5 3 1 叶子节点为：2 4 5 叶子节点个数为：3 二叉树的高度为：3 按层次遍历序列为：1 2 3 4 5 ```