已知一个二叉树的中序遍历序列和后序遍历序列，求这棵树的前序遍历序列,用C语言实现

以下是C语言实现已知一个二叉树的中序遍历序列和后序遍历序列，求这棵树的前序遍历序列的代码：

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

#define MAX_SIZE 100

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

int findIndex(char *arr, int start, int end, char target) {
    for (int i = start; i <= end; i++) {
        if (arr[i] == target) {
            return i;
        }
    }
    return -1;
}

TreeNode *buildTree(char *inorder, char *postorder, int inStart, int inEnd, int postStart, int postEnd) {
    if (inStart > inEnd || postStart > postEnd) {
        return NULL;
    }
    TreeNode *root = (TreeNode *)malloc(sizeof(TreeNode));    root->val = postorder[postEnd];
    int index = findIndex(inorder, inStart, inEnd, postorder[postEnd]);
    root->left = buildTree(inorder, postorder, inStart, index - 1, postStart, postStart + index - inStart - 1);
    root->right = buildTree(inorder, postorder, index + 1, inEnd, postStart + index - inStart, postEnd - 1);
    return root;
}

void preorderTraversal(TreeNode *root) {
    if (root == NULL) {
        return;
    }
    printf("%c ", root->val);
    preorderTraversal(root->left);
    preorderTraversal(root->right);
}

int main() {
    char inorder[MAX_SIZE], postorder[MAX_SIZE];
    scanf("%s %s", inorder, postorder);
    int len = strlen(inorder);
    TreeNode *root = buildTree(inorder, postorder, 0, len - 1, 0, len - 1);
    printf("前序遍历序列为：");
    preorderTraversal(root);
    return 0;
}