Latest Time by Replacing Hidden Digits
<p>You are given a string <code>time</code> in the form of <code> hh:mm</code>, where some of the digits in the string are hidden (represented by <code>?</code>).</p>

<p>The valid times are those inclusively between <code>00:00</code> and <code>23:59</code>.</p>

<p>Return <em>the latest valid time you can get from</em> <code>time</code><em> by replacing the hidden</em> <em>digits</em>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> time = &quot;2?:?0&quot;
<strong>Output:</strong> &quot;23:50&quot;
<strong>Explanation:</strong> The latest hour beginning with the digit &#39;2&#39; is 23 and the latest minute ending with the digit &#39;0&#39; is 50.
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> time = &quot;0?:3?&quot;
<strong>Output:</strong> &quot;09:39&quot;
</pre>

<p><strong class="example">Example 3:</strong></p>

<pre>
<strong>Input:</strong> time = &quot;1?:22&quot;
<strong>Output:</strong> &quot;19:22&quot;
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>time</code> is in the format <code>hh:mm</code>.</li>
	<li>It is guaranteed that you can produce a valid time from the given string.</li>
</ul>
Greedy; String
class Solution:
    def maximumTime(self, time: str) -> str:
        t = list(time)
        if t[0] == '?':
            t[0] = '1' if '4' <= t[1] <= '9' else '2'
        if t[1] == '?':
            t[1] = '3' if t[0] == '2' else '9'
        if t[3] == '?':
            t[3] = '5'
        if t[4] == '?':
            t[4] = '9'
        return ''.join(t)
