请用c语言实现二叉树中序遍历和后续遍历的递归算法和非递归算法。

以下是二叉树中序遍历和后续遍历的递归算法和非递归算法的 C 语言实现：

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

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

// 递归中序遍历
void inorderTraversalRecursive(struct TreeNode* root) {
    if (root == NULL) return;
    inorderTraversalRecursive(root->left);
    printf("%d ", root->val);
    inorderTraversalRecursive(root->right);
}

// 递归后续遍历
void postorderTraversalRecursive(struct TreeNode* root) {
    if (root == NULL) return;
    postorderTraversalRecursive(root->left);
    postorderTraversalRecursive(root->right);
    printf("%d ", root->val);
}

// 非递归中序遍历
void inorderTraversalNonRecursive(struct TreeNode* root) {
    struct TreeNode* stack[100];
    int top = -1;
    while (root || top != -1) {
        while (root) {
            stack[++top] = root;
            root = root->left;
        }
        root = stack[top--];
        printf("%d ", root->val);
        root = root->right;
    }
}

// 非递归后续遍历
void postorderTraversalNonRecursive(struct TreeNode* root) {
    struct TreeNode* stack[100];
    int top = -1;
    struct TreeNode* lastVisit = NULL;
    while (root || top != -1) {
        while (root) {
            stack[++top] = root;
            root = root->left;
        }
        root = stack[top];
        if (root->right == NULL || root->right == lastVisit) {
            printf("%d ", root->val);
            lastVisit = root;
            root = NULL;
            top--;
        } else {
            root = root->right;
        }
    }
}

int main() {
    struct TreeNode* root = (struct TreeNode*)malloc(sizeof(struct TreeNode));
    root->val = 1;
    root->left = (struct TreeNode*)malloc(sizeof(struct TreeNode));
    root->left->val = 2;
    root->left->left = NULL;
    root->left->right = NULL;
    root->right = (struct TreeNode*)malloc(sizeof(struct TreeNode));
    root->right->val = 3;
    root->right->left = (struct TreeNode*)malloc(sizeof(struct TreeNode));
    root->right->left->val = 4;
    root->right->left->left = NULL;
    root->right->left->right = NULL;
    root->right->right = (struct TreeNode*)malloc(sizeof(struct TreeNode));
    root->right->right->val = 5;
    root->right->right->left = NULL;
    root->right->right->right = NULL;

    printf("递归中序遍历: ");
    inorderTraversalRecursive(root);
    printf("\n");

    printf("递归后续遍历: ");
    postorderTraversalRecursive(root);
    printf("\n");

    printf("非递归中序遍历: ");
    inorderTraversalNonRecursive(root);
    printf("\n");

    printf("非递归后续遍历: ");
    postorderTraversalNonRecursive(root);
    printf("\n");

    return 0;
}

输出结果如下：

递归中序遍历: 2 1 4 3 5 
递归后续遍历: 2 4 5 3 1 
非递归中序遍历: 2 1 4 3 5 
非递归后续遍历: 2 4 5 3 1