【解題】二叉探索ツリーの後続遍歴シーケンス(C++実装)

bool isPostorderOfBST(int sequence[], int length)
{
    //    
    if (sequence == NULL || length <= 0)
    {
        return false;
    }

    //            
    int root = sequence[length - 1];

    //     BST           
    int i = 0;
    for (; i < length - 1; i++)
    {
        if (sequence[i] > root)
            break;
    }

    //     BST           
    int j = i;
    for (; j < length - 1; j++)
    {
        if (sequence[j] < root)
            return false;
    }

    //        BST
    bool isLeftBST = true;
    if (i > 0)
    {
        isLeftBST = isPostorderOfBST(sequence, i);
    }

    //        BST
    bool isRightBST = true;
    if (i < length - 1)
    {
        isRightBST = isPostorderOfBST(sequence + i, length - i - 1);
    }

    return (isLeftBST&&isRightBST);
}