在我的笔记本电脑上运行，但在Leetcode上出现运行时错误

Question

我必须从预订和顺序遍历构建一个树。代码在我的笔记本电脑上工作正常，但不在leetcode上。它给出了运行时错误，有什么建议吗？

int findindex(vector<int>& inorder,int index) {
    int size = inorder.size();
    for(int i=0;i<size;i++)
    {
        if(index == inorder[i])
                return index;
    } }

TreeNode* helper(vector<int>& preorder, vector<int>& inorder, int start, int end) {
    static int preindex = 0;
    if(start > end)
        return NULL;
    TreeNode* head;
    head = (TreeNode *)malloc(sizeof(TreeNode));
    head->val = preorder[preindex++];
    head->left = NULL;
    head->right = NULL;
    if(start == end)
        return head;
    int index = findindex(inorder,head->val);

    head->left = helper(preorder, inorder,start, index-1);
    head ->right = helper(preorder, inorder, index+1, end);
    return head; }

TreeNode* Solution::buildTree(vector<int> &preorder, vector<int> &inorder) {
    int size = preorder.size();
    if(size == 0)
        return NULL;
    return helper(preorder, inorder, 0, size-1); }