g1101_1200.s1124_longest_well_performing_interval.Solution Maven / Gradle / Ivy

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Java-based LeetCode algorithm problem solutions, regularly updated

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package g1101_1200.s1124_longest_well_performing_interval;

// #Medium #Array #Hash_Table #Stack #Prefix_Sum #Monotonic_Stack
// #2023_06_01_Time_13_ms_(59.62%)_Space_44.5_MB_(22.12%)

import java.util.HashMap;

/**
 * 1124 - Longest Well-Performing Interval\.
 *
 * Medium
 *
 * We are given `hours`, a list of the number of hours worked per day for a given employee.
 *
 * A day is considered to be a _tiring day_ if and only if the number of hours worked is (strictly) greater than `8`.
 *
 * A _well-performing interval_ is an interval of days for which the number of tiring days is strictly larger than the number of non-tiring days.
 *
 * Return the length of the longest well-performing interval.
 *
 * **Example 1:**
 *
 * **Input:** hours = [9,9,6,0,6,6,9]
 *
 * **Output:** 3
 *
 * **Explanation:** The longest well-performing interval is [9,9,6].
 *
 * **Example 2:**
 *
 * **Input:** hours = [6,6,6]
 *
 * **Output:** 0
 *
 * **Constraints:**
 *
 * *   1 <= hours.length <= 10⁴
 * *   `0 <= hours[i] <= 16`
**/
public class Solution {
    public int longestWPI(int[] hours) {
        int i = 0;
        HashMap map = new HashMap<>();
        int sum = 0;
        map.put(sum, -1);
        int max = Integer.MIN_VALUE;
        for (int val : hours) {
            sum += (val > 8) ? 1 : -1;
            if (!map.containsKey(sum)) {
                map.put(sum, i);
            }
            if (sum > 0) {
                max = i + 1;
            } else if (map.containsKey(sum - 1)) {
                max = Math.max(i - map.get(sum - 1), max);
            }
            i++;
        }
        if (max == Integer.MIN_VALUE) {
            max = 0;
        }
        return max;
    }
}