Very Easy and Fantastic Solve in C language.
Intuition\n Describe your first thoughts on how to solve this problem. \n\n# Approach\n Describe your approach to solving the problem. \n\n# Complexity\n- Time 
# Intuition\n<!-- Describe your first thoughts on how to solve this problem. -->\n\n# Approach\n<!-- Describe your approach to solving the problem. -->\n\n# Complexity\n- Time complexity:\n<!-- Add your time complexity here, e.g. $$O(n)$$ -->O(N)\n\n- Space complexity:\n<!-- Add your space complexity here, e.g. $$O(n)$$ -->O(N)\n\n# Code\n```c []\n/**\n * Definition for a Node.\n * struct Node {\n *     int val;\n *     int numChildren;\n *     struct Node** children;\n * };\n */\n\n/**\n * Note: The returned array must be malloced, assume caller calls free().\n */\nvoid postorderHelper(struct Node* root, int* result, int* returnSize) {\n    if (root == NULL) {\n        return;\n    }\n    for (int i = 0; i < root->numChildren; i++) {\n        postorderHelper(root->children[i], result, returnSize);\n    }\n    result[(*returnSize)++] = root->val;\n}\n\nint* postorder(struct Node* root, int* returnSize) {\n    *returnSize = 0;\n    int* result = (int*)malloc(10000 * sizeof(int)); // Assuming a maximum of 10000 nodes\n    postorderHelper(root, result, returnSize);\n    return result;\n}\n```
['C']