<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) {
         unordered_map<int, int> prefixSumMap;  // Stores the first occurrence of a prefix sum
    int maxLength = 0;
    int prefixSum = 0;
    
    // Iterate through the hours array and update the prefix sum
    for (int i = 0; i < hours.size(); i++) {
        // If hours[i] > 8, it's a tiring day (+1), otherwise it's a non-tiring day (-1)
        if (hours[i] > 8) {
            prefixSum += 1;
        } else {
            prefixSum -= 1;
        }
        
        // If prefix sum is positive, the interval from the start to i is a well-performing interval
        if (prefixSum > 0) {
            maxLength = i + 1;
        } else {
            // If (prefixSum - 1) was seen before, calculate the subarray length
            if (prefixSumMap.find(prefixSum - 1) != prefixSumMap.end()) {
                maxLength = max(maxLength, i - prefixSumMap[prefixSum - 1]);
            }
        }
        
        // Store the first occurrence of the current prefix sum
        if (prefixSumMap.find(prefixSum) == prefixSumMap.end()) {
            prefixSumMap[prefixSum] = i;
        }
    }
    
    return maxLength;

    }
};
27200