<?php

namespace App;

/**
 * Find the Highest Altitude
 *
 * There is a biker going on a road trip. The road trip consists of n + 1 points at different altitudes. The biker
 * starts his trip on point 0 with altitude equal 0. You are given an integer array gain of length n where gain[i] is
 * the net gain in altitude between points i and i + 1 for all (0 <= i < n). Return the highest altitude of a point.
 *
 * Example 1:
 * Input: gain = [-5,1,5,0,-7]
 * Output: 1
 * Explanation: The altitudes are [0,-5,-4,1,1,-6]. The highest is 1.
 *
 * Example 2:
 * Input: gain = [-4,-3,-2,-1,4,3,2]
 * Output: 0
 * Explanation: The altitudes are [0,-4,-7,-9,-10,-6,-3,-1]. The highest is 0.
 *
 * https://leetcode.com/problems/find-the-highest-altitude
 */
class FindHighestAltitude
{
    /**
     * @param int[] $gain
     * @return int
     */
    public function largestAltitude(array $gain): int
    {
        $max = 0;
        $currentAltitude = 0;
        foreach ($gain as $altitude) {
            $currentAltitude += $altitude;
            if ($currentAltitude > $max) {
                $max = $currentAltitude;
            }
        }
        return $max;
    }
}
