<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>

class Solution {
public:
    string maximumTime(string s) {
		int time[] = {'5', '9'};
        for (int i = 0; i < 5; i++) {
			if (s[i] == '?') {
				if (i == 0)  {
					if (s[i+1] == '?' || s[i+1] <= '3')
						s[i] = '2';
					else if (s[i+1] > '3')
						s[i] = '1';
				}

				else if (i == 1) {
					if (s[i-1] == '2')
						s[i] = '3';
					else
						s[i] = '9';
				}

				else
					s[i] = time[i-3];
			}
		}

		return s;
    }
};
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