Solution.java

import java.util.LinkedList;
import java.util.Scanner;
import java.util.Stack;

public class Solution {

	public static Scanner sc = new Scanner(System.in);
	public static Stack<Solution.Node> stack = null;
	public static int ans = -1;
   public static void main(String[] args){
	   stack = new Stack<Solution.Node>();
	   
	   String line1 = sc.nextLine();
	   int N = Integer.parseInt(line1);
	   Solution.Node[] input = new Solution.Node[N];
	   
	   String line2 = sc.nextLine();
	   String[] splittedInput=line2.split(" ");
	   
	   int index=0;
	   for(String s : splittedInput){
		   int poisonAmnt = Integer.parseInt(s);
		   input[index] = new Solution().new Node(poisonAmnt, -1);
		   index++;
	   }
	   
	   int elementIndex = 0;
	   while(elementIndex<N){
		   Node currentNode = input[elementIndex];
		   if(stack.isEmpty()){
			   currentNode.setDay(0);
			   ans= max(ans, 0);
			   stack.push(currentNode);
		   }
		   
		   else if(currentNode.getPoisonAmt()>stack.peek().getPoisonAmt()){
			   currentNode.setDay(1);
			   ans= max(ans, 1);
			   stack.push(currentNode);
		   }
		   
		   else if(currentNode.getPoisonAmt()<stack.peek().getPoisonAmt()){
			   int maxDay = 0;
			   while(!stack.isEmpty() && (stack.peek().getPoisonAmt()>currentNode.getPoisonAmt())){
				   Node topElement = stack.pop();
				   maxDay=max(maxDay, topElement.getDay());
			   }
			   
			   if(stack.isEmpty()){
				   currentNode.setDay(0);
				   ans= max(ans, 0);
				   stack.push(currentNode);
			   }
			   else{
				   currentNode.setDay(maxDay+1);
				   ans= max(ans, maxDay+1);
				   stack.push(currentNode);
			   }
		   }
		   elementIndex++; 
	   }
	   
	System.out.println(ans);   
   }
   
   private static int max(int maxDay, int day) {
	if(maxDay>day){
		return maxDay;
	}
	else{
		return day;
	}
}

private class Node{
	   private int poisonAmt;
	   private int day=-1;
	   
	   public Node(int poisonAmt, int day){
		   this.poisonAmt=poisonAmt;
		   this.day=day;
	   }

	public void setDay(int i) {
		this.day=i;		
	}
	
	public int getDay(){
		return this.day;
	}
	
	public int getPoisonAmt(){
		return this.poisonAmt;
	}
   }
   
}