Construct Binary Tree From Inorder and Preorder/Postorder Traversal

map<int, int> mapIndex;
void mapToIndex(int inorder[], int n)
{
    for (int i = ; i < n; i++)
    {
        mapIndex.insert(map<int, int>::value_type(inorder[i], i);
    }
}

Node* buildInorderPreorder(int in[], int pre[], int n, int offset)
{
    assert(n >= );
    if (n == )
        return NULL;
    int rootVal = pre[];
    int i = mapIndex[rootVal] - offset;
    Node* root = new Node(rootVal);
    root->left = buildInorderPreorder(in, pre+, i, offset);
    root->right = buildInorderPreorder(in+i+, pre+i+, n-i-, offset+i+);
    return root;
}

Node* buildInorderPostorder(int in[], int post[], int n, int offset)
{
    assert(n >= );
    if (n == )
        return NULL;
    int rootVal = post[n-];
    int i = mapIndex[rootVal] - offset;
    Node* root = new Node(rootVal);
    root->left = buildInorderPostorder(in, post, i, offset);
    root->right = buildINorderPostorder(in+i+, post+i, n-i-, offset+i+);
    return root;
}