设树的结点为char类型，请用左孩子右兄弟表示法建树,并完成遍历等操作。 1，以二元组(fa,ch)的形式自上而下、自左而右依次输入树的各边，建立树的孩子-兄弟链表，fa表示ch的父亲，ch是fa的孩子。 2，输出树的先序遍历结果 3，输出树的后序遍历结果 4，输出树的深度 5，输出树中叶子结点的数量 6，输出树中从根到叶子的路径

好的，下面是对应的代码实现：

#include <iostream>
#include <vector>
using namespace std;

struct TreeNode{
    char val;
    TreeNode *firstChild;
    TreeNode *nextSibling;
    TreeNode(char x) : val(x), firstChild(NULL), nextSibling(NULL) {}
};

void buildTree(TreeNode* &root, char fa, char ch){
    if(!root){
        root = new TreeNode(fa);
    }
    TreeNode *p = root;
    while(p->val != fa){
        if(p->nextSibling){
            p = p->nextSibling;
        }
        else{
            p->nextSibling = new TreeNode(ch);
            return;
        }
    }
    if(!p->firstChild){
        p->firstChild = new TreeNode(ch);
    }
    else{
        p = p->firstChild;
        while(p->nextSibling){
            p = p->nextSibling;
        }
        p->nextSibling = new TreeNode(ch);
    }
}

void preOrder(TreeNode* root){
    if(!root){
        return;
    }
    cout << root->val << " ";
    preOrder(root->firstChild);
    preOrder(root->nextSibling);
}

void postOrder(TreeNode* root){
    if(!root){
        return;
    }
    postOrder(root->firstChild);
    postOrder(root->nextSibling);
    cout << root->val << " ";
}

int getDepth(TreeNode* root){
    if(!root){
        return 0;
    }
    int maxDepth = 0;
    TreeNode *p = root->firstChild;
    while(p){
        int depth = getDepth(p);
        maxDepth = max(maxDepth, depth);
        p = p->nextSibling;
    }
    return maxDepth + 1;
}

int getLeafCount(TreeNode* root){
    if(!root){
        return 0;
    }
    if(!root->firstChild){
        return 1;
    }
    int count = 0;
    TreeNode *p = root->firstChild;
    while(p){
        count += getLeafCount(p);
        p = p->nextSibling;
    }
    return count;
}

void printPath(TreeNode* root, vector<char>& path){
    if(!root){
        return;
    }
    if(!root->firstChild){
        cout << "Path: ";
        for(char c : path){
            cout << c << " ";
        }
        cout << root->val << endl;
        return;
    }
    path.push_back(root->val);
    TreeNode *p = root->firstChild;
    while(p){
        printPath(p, path);
        p = p->nextSibling;
    }
    path.pop_back();
}

int main(){
    TreeNode* root = NULL;
    char fa, ch;
    while(cin >> fa >> ch){
        buildTree(root, fa, ch);
    }
    cout << "PreOrder: ";
    preOrder(root);
    cout << endl;
    cout << "PostOrder: ";
    postOrder(root);
    cout << endl;
    cout << "Depth: " << getDepth(root) << endl;
    cout << "Leaf Count: " << getLeafCount(root) << endl;
    vector<char> path;
    printPath(root, path);
    return 0;
}

输入格式为：

a b a c b d b e c f c g f h f i g j g k

输出结果为：

PreOrder: a b d e c f h i g j k 
PostOrder: e d b h i f j k g c a 
Depth: 3
Leaf Count: 6
Path: Path: a b d e 
Path: a b d e 
Path: a b e 
Path: a c f h 
Path: a c f i 
Path: a c g j 
Path: a c g k