Construct Binary Tree from Preorder and Inorder Traversal

Given preorder and inorder traversal of a tree, construct the binary tree.

Note:
You may assume that duplicates do not exist in the tree.

#include<stdio.h>#include<stdlib.h>typedef struct TreeNode {   int val;   struct TreeNode *left;   struct TreeNode *right;}TreeNode;TreeNode *buildTreeCore(int *preorder, int prebegin, int preend, int *inorder, int inbegin, int inend) {    TreeNode *root = (TreeNode *)malloc(sizeof(TreeNode));    root->val = preorder[prebegin];    root->left = root->right = NULL;    //printf("%d ", root->val);    if(prebegin == preend || inbegin == inend) return root;    int i;    for(i = inbegin; i <= inend && inorder[i] != preorder[prebegin]; i++) ;    if(i > inbegin) {        root->left = buildTreeCore(preorder, prebegin + 1, prebegin + i, inorder, inbegin, i - 1);    }    if(i < inend) {        root->right = buildTreeCore(preorder, prebegin + i + 1, preend, inorder, i + 1,inend);    }    return root;}TreeNode *buildTree(int *preorder, int *inorder, int n) {    if(preorder == NULL || inorder == NULL) return NULL;    TreeNode *root =  buildTreeCore(preorder, 0, n - 1, inorder, 0, n - 1);    return root;}void Travel(TreeNode *root) {    if(root != NULL) {        Travel(root->left);        Travel(root->right);        printf("%d,", root->val);    }}void main() {    int pre[] = {-1};    int in[] = {-1};    TreeNode* root = buildTree(pre, in, 1);    Travel(root); }