编写二叉树的递归遍历算法，给定二叉树的扩展先序遍历序列，输出二叉树的先序遍历，中序遍历和后序遍历的结点序列和叶子结点和和结点个数的c语言代码

以下是对应的 C 语言代码：

#include <stdio.h>
#include <stdlib.h>

typedef struct TreeNode {
    int val;
    struct TreeNode* left;
    struct TreeNode* right;
} TreeNode;

// 创建一棵二叉树
TreeNode* createTree(int* pos) {
    char* s = "AB##C##";
    char ch = s[(*pos)++];
    if (ch == '#') {
        return NULL;
    }
    TreeNode* root = (TreeNode*)malloc(sizeof(TreeNode));
    root->val = ch;
    root->left = createTree(pos);
    root->right = createTree(pos);
    return root;
}

// 先序遍历
void preOrder(TreeNode* root) {
    if (root == NULL) {
        return;
    }
    printf("%c ", root->val);
    preOrder(root->left);
    preOrder(root->right);
}

// 中序遍历
void inOrder(TreeNode* root) {
    if (root == NULL) {
        return;
    }
    inOrder(root->left);
    printf("%c ", root->val);
    inOrder(root->right);
}

// 后序遍历
void postOrder(TreeNode* root) {
    if (root == NULL) {
        return;
    }
    postOrder(root->left);
    postOrder(root->right);
    printf("%c ", root->val);
}

// 计算叶子结点个数
int countLeaves(TreeNode* root) {
    if (root == NULL) {
        return 0;
    }
    if (root->left == NULL && root->right == NULL) {
        return 1;
    }
    return countLeaves(root->left) + countLeaves(root->right);
}

// 计算结点个数
int countNodes(TreeNode* root) {
    if (root == NULL) {
        return 0;
    }
    return countNodes(root->left) + countNodes(root->right) + 1;
}

int main() {
    int pos = 0;
    TreeNode* root = createTree(&pos);

    printf("先序遍历：");
    preOrder(root);
    printf("\n");

    printf("中序遍历：");
    inOrder(root);
    printf("\n");

    printf("后序遍历：");
    postOrder(root);
    printf("\n");

    printf("叶子结点个数：%d\n", countLeaves(root));
    printf("结点个数：%d\n", countNodes(root));

    return 0;
}