using System;

using System.Collections.Generic;

​

public class Program

{

​

    public static void Main()

    {

// Generate 10 distinct random numbers in the range of 1 to 20. 

        //Each random number is associated with a prize money (from 1 to 10000).

        // Use a Dictionary to store the mapping between the random number and the prize money.

        Dictionary<int, int> dict = new Dictionary<int, int>(); // declare Dictionary which is a hashtable

        Random rand = new Random();//Random(0)--> have seed "0", thus will have fixed set of random values; empty then will be diff

        while (dict.Count < 10)

        {

            //check if it is distinct number

            int nos = rand.Next(1, 20);

            int val = rand.Next(1, 10000);

            if (!dict.ContainsKey(nos))// if double quote, it is a string, not int

            {

                dict.Add(nos, val);

            }

        }

​

// Verify by printing out the random number list

        Dictionary<int, int>.KeyCollection keys = dict.Keys;

        foreach (int no in keys)// how to know  keys is the first or the second one?  // foreach(vartype variablename(you give a name to call every element inside keys) in keys(the keycollection's name)

        {

            Console.WriteLine("{0}", no);

        }

​

//Ask user for a number from 1 to 20

        // how to parse a string into an integer

        Console.WriteLine("Please input an integer");

        string input = Console.ReadLine(); //will read a whole line as a string

        //only 1 number is inputted, so no need to use foreach

        int number;//let number for storing input

        bool success = int.TryParse(input, out number); // [int. is ]TryParse returns true if successfully converted s into an int 

        // the converted int is put into the second parameter using keyword "out"   

// do you know why "out" is used here? why not return the converted integer???????

        //If the Dictionary does not contain the number, print "BANG! You die!"

        //If the Dictionary have the number, print "You earned XXXXX dollars!" where XXXXX is

        //the amount of associated prize money

        Dictionary<int, int>.KeyCollection keyss = dict.Keys;///Dictionary<int, int>.KeyCollection --> a long class , var is keyss

        if (dict.ContainsKey(number))

        {

            Console.WriteLine("You earned {0} dollars!", +dict[number]);

        }

        else

        {

            Console.WriteLine("BANG! You die!");

        }

    }

}

//"Random rand =new Random(0);

//Count, ContainsKey, Add

​