### Problem 2: Repeated Implement `repeated`, which takes in an iterator `t` and returns the first value in `t` that appears `k` times in a row. > **Note:** You can assume that the iterator `t` will have a value that appears at least `k` times in a row. If you are receiving a `StopIteration`, your `repeated` function is likely not identifying the correct value. Your implementation should iterate through the items in a way such that if the same iterator is passed into `repeated` twice, it should continue in the second call at the point it left off in the first. An example of this behavior is in the doctests. ```python def repeated(t, k): """Return the first value in iterator T that appears K times in a row. Iterate through the items such that if the same iterator is passed into the function twice, it continues in the second call at the point it left off in the first. >>> s = iter([10, 9, 10, 9, 9, 10, 8, 8, 8, 7]) >>> repeated(s, 1) 10 >>> repeated(s, 2) 9 >>> s2 = iter([10, 9, 10, 9, 9, 10, 8, 8, 8, 7]) >>> repeated(s2, 3) 8 >>> s = iter([3, 2, 2, 2, 2, 2, 2, 4, 4, 5, 5, 5]) >>> repeated(s, 3) 2 >>> repeated(s, 3) 2 >>> repeated(s, 3) 5 >>> s2 = iter([4, 1, 6, 6, 7, 7, 8, 8, 2, 2, 2, 5]) >>> repeated(s2, 3) 2 """ assert k >= 1 "*** YOUR CODE HERE ***" ```

def repeated(t, k):
    assert k >= 1
    count = 1
    prev_val = next(t)
    for val in t:
        if val == prev_val:
            count += 1
            if count == k:
                return val
        else:
            count = 1
        prev_val = val
    # If we reach the end of the iterator and no value appears k times in a row, raise an error
    raise ValueError(f"No value appears {k} times in a row")

思路：

首先，我们要在函数的开头断言 $k\geq1$，因为该函数无法处理 $k<1$ 的情况。

我们可以迭代给定的迭代器 $t$，并跟踪当前正在查看的值和此值已经连续出现的次数。 如果下一个值等于当前值，则增加计数器 $count$，否则重置 $count$ 为1。 如果 $count$ 达到 $k$，则返回当前值。 如果我们迭代完整个列表都没有找到重复 $k$ 次的值，则引发 `ValueError`。

最后，我们需要确保如果相同的迭代器两次传入 `repeated` 函数，则第二次调用从上一次结束的地方继续执行。

相关问题

Implement repeated, which takes in an iterator t and returns the first value in t that appears k times in a row.

Sure, here's a possible implementation of the `repeated` function in Python:

def repeated(t, k):
    last = None
    count = 0
    for item in t:
        if item == last:
            count += 1
        else:
            last = item
            count = 1
        if count == k:
            return item
    return None

The `repeated` function takes two arguments: `t` is the iterator we want to search for repeated values, and `k` is the number of times a value must appear in a row to be considered repeated. The function initializes a `last` variable to `None` to keep track of the last value seen, and a `count` variable to 0 to keep track of the number of times the last value has been seen in a row. The function iterates over the items in `t` and updates the `last` and `count` variables accordingly. If the `count` variable reaches `k`, the function returns the current item (i.e., we have found a repeated value). If we reach the end of the iterator without finding a repeated value, the function returns `None`.

For example, we can use the function like this:

it = iter([1, 2, 3, 3, 3, 4, 4, 5, 5, 5, 5])
print(repeated(it, 3))  # Output: 3

In this example, we create an iterator `it` over a list with repeated values. We then call `repeated(it, 3)` to search for a value that appears 3 times in a row, and it returns 3.

org.apache.hadoop.hive.ql.parse.SemanticException:Column repeated in partitioning columns

这个异常通常在Hive中使用分区表时出现，它意味着你在定义分区表时，多次使用了相同的分区列。分区列是在表的CREATE语句中指定的，用于将表数据分隔成不同的分区。每个分区都必须由唯一的分区列组合来定义。

要解决这个问题，你需要检查你的表定义，确保你没有在分区列中重复使用相同的列名。如果你有多个分区列，它们应该是唯一的。你可以尝试重新定义表，删除重复的分区列，或者将它们合并成一个列列表。例如：

CREATE TABLE mytable (
  col1 STRING,
  col2 INT
)
PARTITIONED BY (year INT, month INT, day INT);

在这个例子中，我们定义了一个名为mytable的表，其中包含两个列（col1和col2），并且使用year、month和day作为分区列。注意，我们没有重复使用任何列名。