<p>We are given <code>hours</code>, a list of the number of hours worked per day for a given employee.</p>

<p>A day is considered to be a <em>tiring day</em> if and only if the number of hours worked is (strictly) greater than <code>8</code>.</p>

<p>A <em>well-performing interval</em> is an interval of days for which the number of tiring days is strictly larger than the number of non-tiring days.</p>

<p>Return the length of the longest well-performing interval.</p>

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

<pre>
<strong>Input:</strong> hours = [9,9,6,0,6,6,9]
<strong>Output:</strong> 3
<strong>Explanation: </strong>The longest well-performing interval is [9,9,6].
</pre>

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

<pre>
<strong>Input:</strong> hours = [6,6,6]
<strong>Output:</strong> 0
</pre>

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

<ul>
	<li><code>1 &lt;= hours.length &lt;= 10<sup>4</sup></code></li>
	<li><code>0 &lt;= hours[i] &lt;= 16</code></li>
</ul>

class Solution {
public:
    int longestWPI(vector<int>& hours) {
        map<int, int> leastNums;
        leastNums.insert({0, 0});
        int prefix = 0, maxInvLength = 0;
        int minValue = 0;

        for (int i=0; i<hours.size(); i++) {
            prefix = (hours[i] > 8) - (hours[i] <= 8) + prefix;
            if (prefix < minValue) {
                leastNums.insert({prefix, i+1});
                minValue = prefix;
            }
            
            if (prefix > 0 )
                maxInvLength = i+1;
            else {
                auto ne = leastNums.lower_bound(prefix);
                if (ne != leastNums.end() && ne != leastNums.begin()) {
                    auto prev = std::prev(ne);
                    int interval = i - prev->second + 1;
                    if (interval > maxInvLength)
                        maxInvLength = interval;
                }
            }
        }

        return maxInvLength;
    }
};
26000