请将上面的代码转换为C语言

好的，根据您的要求，我将上面的Python代码转换成C语言代码。下面是转换后的代码：

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

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

TreeNode* create_node(int val) {
    TreeNode* node = (TreeNode*) malloc(sizeof(TreeNode));
    node->val = val;
    node->left = NULL;
    node->right = NULL;
    return node;
}

bool is_same_tree(TreeNode* root1, TreeNode* root2) {
    if (!root1 && !root2) {
        return true;
    } else if (!root1 || !root2) {
        return false;
    } else if (root1->val != root2->val) {
        return false;
    } else {
        return is_same_tree(root1->left, root2->left) && is_same_tree(root1->right, root2->right);
    }
}

TreeNode* insert_node(TreeNode* root, int val) {
    if (!root) {
        return create_node(val);
    } else if (val < root->val) {
        root->left = insert_node(root->left, val);
    } else {
        root->right = insert_node(root->right, val);
    }
    return root;
}

TreeNode* build_tree(int* nums, int n) {
    TreeNode* root = NULL;
    for (int i = 0; i < n; i++) {
        root = insert_node(root, nums[i]);
    }
    return root;
}

void postorder(TreeNode* root, int* res, int* returnSize) {
    if (!root) {
        return;
    }
    postorder(root->left, res, returnSize);
    postorder(root->right, res, returnSize);
    res[(*returnSize)++] = root->val;
}

void levelorder(TreeNode* root, int* res, int* returnSize) {
    int front = 0, rear = -1;
    TreeNode* queue[1000];
    if (root) {
        queue[++rear] = root;
    }
    while (front <= rear) {
        TreeNode* node = queue[front++];
        res[(*returnSize)++] = node->val;
        if (node->left) {
            queue[++rear] = node->left;
        }
        if (node->right) {
            queue[++rear] = node->right;
        }
    }
}

int main() {
    int n;
    scanf("%d", &n);

    int nums1[1000], nums2[1000];
    for (int i = 0; i < n; i++) {
        scanf("%d", &nums1[i]);
    }
    for (int i = 0; i < n; i++) {
        scanf("%d", &nums2[i]);
    }

    TreeNode* root1 = build_tree(nums1, n);
    TreeNode* root2 = build_tree(nums2, n);

    if (is_same_tree(root1, root2)) {
        printf("YES\n");

        int res1[1000], res2[1000];
        int returnSize1 = 0, returnSize2 = 0;
        postorder(root1, res1, &returnSize1);
        levelorder(root1, res2, &returnSize2);

        for (int i = 0; i < n; i++) {
            printf("%d", res1[i]);
            if (i != n - 1) {
                printf(" ");
            }
        }
        printf("\n");
        for (int i = 0; i < n; i++) {
            printf("%d", res2[i]);
            if (i != n - 1) {
                printf(" ");
            }
        }
        printf("\n");
    } else {
        printf("NO\n");
    }

    return 0;
}

在C语言中，没有Python中那么方便的内置数据类型和函数，因此需要自己实现树的节点结构、插入节点、后序遍历、层序遍历等函数，代码可能会比Python代码略显繁琐。但是，C语言作为一种底层语言，运行速度更快，更加适合处理一些计算密集型的任务。