[백준 / C#] 1927 : 최소 힙

using System;
using System.Collections.Generic;
using System.Text;
using System.IO;

namespace _11279
{
    class MaxHeap
    {
        private List<int> A = new List<int>();

        public void Add(int value)
        {
            // Add the end
            A.Add(value);
            // bubble up(부모노드 찾기)
            int i = A.Count - 1;
            while (i > 0)
            {
                int parent = (i - 1) / 2;
                if (A[parent] > A[i])               // Max Heap일때는 부등호를 반대
                {
                    Swap(parent, i);
                    i = parent;
                }
                else break;
            }
        }
        public int RemoveOne()
        {
            if (A.Count.Equals(0))
                return 0;

            //Min Heap
            int root = A[0];

            A[0] = A[A.Count - 1];
            A.RemoveAt(A.Count - 1);

            // bubble down
            int i = 0;
            int last = A.Count - 1;
            while (i < last)
            {
                int child = i * 2 + 1;
                if (child < last && 
                    A[child] > A[child + 1]) //Max Heap일때는 반대
                    child = child + 1;
                if (child > last || 
                    A[i] <= A[child])  //Max Heap일때는 반대
                    break;
                Swap(i, child);
                i = child;
            }
            return root;
        }
        private void Swap(int i, int j)
        {
            int t = A[i];
            A[i] = A[j];
            A[j] = t;
        }
    }
    class Program
    {
        static int n;
        static StringBuilder sb = new StringBuilder();
        static MaxHeap item = new MaxHeap();
        static void Solution(int n)
        {
            if (n.Equals(0))
                sb.AppendLine(item.RemoveOne().ToString());
            else item.Add(n);
        }
        static void Input()
        {
            StreamReader sr = new StreamReader(Console.OpenStandardInput());
            n = int.Parse(sr.ReadLine());
            for (int i = 0; i < n; i++)
                Solution(int.Parse(sr.ReadLine()));
            Console.WriteLine(sb);
        }
        static void Solve()
        {
            Input();
        }
        static void Main(string[] args)
        {
            Solve();
        }
    }
}