Implementation of variation of 'The stock span problem'

algorithms-stack-poisoned-plants.cs

// https://www.hackerrank.com/challenges/poisonous-plants/submissions/code/31921305
// Stack will be used to track series of plants splitted by the survived plants.
// Stack is a tuple of index of plant and amount of day that it will servive (0 - will live forever).
//  eaxamle input: 3 7 1 2 4 8 2 7 9
// serie splitter: |   | 
//          index: 0 1 2 3 4 5 6 7 8
// amount of days: 0 1 0 1 1 1 2 1 1
//        maximum: 2
public int PoisonousPlants(string input)
{
    var plants = input
        .Split(new[] { ' ' }, StringSplitOptions.RemoveEmptyEntries)
        .Select(int.Parse)
        .ToArray();
    
    var stack = new Stack<Tuple<int, int>>();
    stack.Push(new Tuple<int, int>(0, 0));
    var maxDays = 0;
    for (int i = 1; i < plants.Length; i++)
    {
        int days = 0;
        while (stack.Count > 0 && plants[stack.Peek().Item1] >= plants[i])
        {
            days = Math.Max(days, stack.Pop().Item2);
        }
        days = stack.Count == 0 ? 0 : (days + 1);
        maxDays = Math.Max(maxDays, days);
        stack.Push(new Tuple<int, int>(i, days));
     }
     return maxDays;
}