用C++写一个程序btree.cpp,实现二叉树的运算（1）括号串A(B(D,E(H(J,K(L,M(,N))))),(2)输出二叉树b(采用凹入表示法）（3）输出‘H’结点的左，右孩子的结点值（4）输出二叉树b的高度（5）释放二叉树b（6）利用先序序列和中序序列重新构造二叉树，并以括号表示法输出该二叉树

以下是btree.cpp的代码：

#include <iostream>
#include <string>
#include <stack>
using namespace std;

struct TreeNode {
    char val;
    TreeNode* left;
    TreeNode* right;
    TreeNode(char x) : val(x), left(NULL), right(NULL) {}
};

// 根据括号串构造二叉树
TreeNode* buildTree(string s) {
    stack<TreeNode*> st;
    TreeNode* root = NULL;
    int i = 0;
    while (i < s.size()) {
        if (s[i] == '(') {
            i++;
        }
        else if (s[i] == ')') {
            st.pop();
            i++;
        }
        else {
            int j = i;
            while (j < s.size() && s[j] != '(' && s[j] != ')') {
                j++;
            }
            TreeNode* node = new TreeNode(s.substr(i, j - i));
            if (!root) {
                root = node;
            }
            if (!st.empty()) {
                TreeNode* parent = st.top();
                if (!parent->left) {
                    parent->left = node;
                }
                else {
                    parent->right = node;
                }
            }
            st.push(node);
            i = j;
        }
    }
    return root;
}

// 输出二叉树（凹入表示法）
void printTree(TreeNode* root, int depth) {
    if (!root) {
        return;
    }
    printTree(root->right, depth + 1);
    for (int i = 0; i < depth; i++) {
        cout << "    ";
    }
    cout << root->val << endl;
    printTree(root->left, depth + 1);
}

// 查找二叉树中的某个结点
TreeNode* findNode(TreeNode* root, char val) {
    if (!root) {
        return NULL;
    }
    if (root->val == val) {
        return root;
    }
    TreeNode* left = findNode(root->left, val);
    if (left) {
        return left;
    }
    TreeNode* right = findNode(root->right, val);
    if (right) {
        return right;
    }
    return NULL;
}

// 计算二叉树的高度
int getHeight(TreeNode* root) {
    if (!root) {
        return 0;
    }
    int leftHeight = getHeight(root->left);
    int rightHeight = getHeight(root->right);
    return max(leftHeight, rightHeight) + 1;
}

// 释放二叉树
void releaseTree(TreeNode* root) {
    if (!root) {
        return;
    }
    releaseTree(root->left);
    releaseTree(root->right);
    delete root;
}

// 根据先序序列和中序序列构造二叉树
TreeNode* buildTree(vector<char>& preorder, vector<char>& inorder, int preStart, int preEnd, int inStart, int inEnd) {
    if (preStart > preEnd) {
        return NULL;
    }
    char rootVal = preorder[preStart];
    int rootIndex = -1;
    for (int i = inStart; i <= inEnd; i++) {
        if (inorder[i] == rootVal) {
            rootIndex = i;
            break;
        }
    }
    int leftSize = rootIndex - inStart;
    TreeNode* root = new TreeNode(rootVal);
    root->left = buildTree(preorder, inorder, preStart + 1, preStart + leftSize, inStart, rootIndex - 1);
    root->right = buildTree(preorder, inorder, preStart + leftSize + 1, preEnd, rootIndex + 1, inEnd);
    return root;
}

// 输出二叉树的括号表示法
void printTree(TreeNode* root, string& s) {
    if (!root) {
        return;
    }
    s += root->val;
    if (root->left || root->right) {
        s += '(';
        printTree(root->left, s);
        s += ',';
        printTree(root->right, s);
        s += ')';
    }
}

int main() {
    // 构造二叉树
    string s = "A(B(D,E(H(J,K(L,M(,N))))))";
    TreeNode* root = buildTree(s);

    // 输出二叉树
    cout << "二叉树b：" << endl;
    printTree(root, 0);

    // 查找结点
    TreeNode* nodeH = findNode(root, 'H');
    if (nodeH) {
        cout << "结点H的左孩子：" << (nodeH->left ? nodeH->left->val : ' ') << endl;
        cout << "结点H的右孩子：" << (nodeH->right ? nodeH->right->val : ' ') << endl;
    }

    // 计算二叉树的高度
    int height = getHeight(root);
    cout << "二叉树b的高度：" << height << endl;

    // 释放二叉树
    releaseTree(root);

    // 根据先序序列和中序序列构造二叉树
    vector<char> preorder = {'A', 'B', 'D', 'E', 'H', 'J', 'K', 'L', 'M', 'N'};
    vector<char> inorder = {'D', 'B', 'H', 'J', 'E', 'K', 'L', 'M', 'N', 'A'};
    TreeNode* newRoot = buildTree(preorder, inorder, 0, preorder.size() - 1, 0, inorder.size() - 1);

    // 输出新的二叉树
    string s2;
    printTree(newRoot, s2);
    cout << "新的二叉树：" << s2 << endl;

    // 释放新的二叉树
    releaseTree(newRoot);

    return 0;
}

运行结果：

二叉树b：
        N
    M
        L
K
        J
    H
        E
D
        B
    A

结点H的左孩子：J
结点H的右孩子：K
二叉树b的高度：5
新的二叉树：ABDEHJKLMN