已知二叉树中序后序去推前序c语言

下面是一个递归实现的示例代码：

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

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

// 根据中序序列和后序序列构建二叉树
TreeNode* buildTree(char* inorder, char* postorder, int length) {
    if (length <= 0) {
        return NULL;
    }

    TreeNode* root = (TreeNode*)malloc(sizeof(TreeNode));
    root->data = postorder[length - 1];

    int i;
    for (i = 0; i < length; i++) {
        if (inorder[i] == root->data) {
            break;
        }
    }

    root->left = buildTree(inorder, postorder, i);
    root->right = buildTree(inorder + i + 1, postorder + i, length - i - 1);

    return root;
}

// 前序遍历二叉树
void preorderTraversal(TreeNode* root) {
    if (root == NULL) {
        return;
    }

    printf("%c ", root->data);
    preorderTraversal(root->left);
    preorderTraversal(root->right);
}

int main() {
    char inorder[] = "DBEAFC";
    char postorder[] = "DEBFCA";
    int length = sizeof(inorder) / sizeof(char);

    TreeNode* root = buildTree(inorder, postorder, length);
    printf("前序遍历结果为：");
    preorderTraversal(root);
    printf("\n");

    return 0;
}

这里假设输入的中序序列和后序序列中不包含重复元素，且输入合法。如果需要自己输入序列，可以使用 scanf 函数。