HOMEWORKS

Оператори и изрази///////////////////////////////////////////////////////////////////////////////////////////////////////////////

using System;
2
 5 problem IsThirdDigit7

3 class IsThirdDigit7
4 {
5     //Write an expression that checks for given integer if its third digit from right-to-left is 7.
6     static void Main(string[] args)
7     {
8         Console.WriteLine("Enter an integer number:");
9         int number = int.Parse(Console.ReadLine());
10         int pathToDigit = number / 100;
11         int thirdDigit = pathToDigit % 10;
12         bool isSeven = thirdDigit == 7;
13         Console.WriteLine("Is the third digit 7?\n" + isSeven);
14     }
15 }


7 point in a circle

using System;
2

3 class PointInACircle
4 {
5     //Write an expression that checks if given point (x,  y) is inside a circle K({0, 0}, 2).
6     static void Main(string[] args)
7     {
8         Console.WriteLine("Enter coordinate x of the point");
9         decimal pointX = decimal.Parse(Console.ReadLine());
10         Console.WriteLine("Enter coordinate y of the point");
11         decimal pointY = decimal.Parse(Console.ReadLine());
12         byte radius = 2;
13         //Pythagorean Theorem a^2 + b^2 = c^2 ==> (x*x) + (y*y) <= radius * radius.
14         //Operator * is faster than Math.Pow()
15         bool isInCircle = pointX * pointX + pointY * pointY <= radius * radius;
16         Console.WriteLine("Is the given point in the circle?\n{0}", isInCircle);
17     }
18 }


8 prime number chek

using System;
2

3 class PrimeNumberCheck
4 {
5     //Write an expression that checks if given positive integer number n (n ≤ 100) is prime (i.e. it is divisible without
6     //remainder only to itself and 1).
7     static void Main(string[] args)
8     {
9         Console.WriteLine("Enter positive integer number n between 2 and 100");
10         int numberN = int.Parse(Console.ReadLine());
11         while (numberN < 2 || numberN > 100)
12         {
13             Console.WriteLine("Try again");
14             numberN = int.Parse(Console.ReadLine());
15         }
16         bool isPrime = true;
17         int counter = 1;
18         //Trial division
19         while (counter <= Math.Sqrt(numberN))
20         {
21             if (numberN % counter == 0 && counter > 1)
22             {
23                 isPrime = false;
24             }
25             counter++;
26         }
27         Console.WriteLine("Is your number prime?\n{0}", isPrime);
28     }
29 }


10 10.InsideCircleOutsideRectangle

using System;
2

3 class InsideCircleOutsideRectangle
4 {
5     //Write an expression that checks for given point (x, y) if it is within the circle K({1, 1}, 1.5) and out of the rectangle
6     //R(top=1, left=-1, width=6, height=2).
7     static void Main(string[] args)
8     {
9         Console.WriteLine("Enter coordinate x of the point");
10         decimal pointX = decimal.Parse(Console.ReadLine());
11         Console.WriteLine("Enter coordinate y of the point");
12         decimal pointY = decimal.Parse(Console.ReadLine());
13         decimal radius = 1.5m;
14         //Pythagorean Theorem a^2 + b^2 = c^2 ==> (x*x) + (y*y) <= radius * radius.
15         //Operator * is faster than Math.Pow()
16         bool isInCircle = (pointX - 1) * (pointX - 1) + (pointY - 1) * (pointY - 1) <= radius * radius;
17         //Every y below 1 is in the rectangle or outside the circle, or both.
18         if (isInCircle && pointY > 1)
19         {
20             Console.WriteLine("YES");
21         }
22         else
23         {
24             Console.WriteLine("NO");
25         }
26     }
27 }


C# Homework: Console Input / Output 1-11/////////////////////////////////////////////////////////////////////////////////////////////////////


8 Problem 8.    Numbers from 1 to n


3.class NumberFromOneToN
4.{
5.    static void Main()
6.    {
7.        Console.Write("n=");
8.        int n = int.Parse(Console.ReadLine());
9.        for (int i = 1; i <= n; i++)
10.        {
11.            Console.WriteLine(i);
12.        }
13.    }
14.}

9 Problem 9.    Sum of n Numbers

class SumOfNumbers

5.    static void Main()
6.    {
7.        Console.Write("n=");
8.        int n = int.Parse(Console.ReadLine());
9.        double sum = 0;
10.        for (int i = 1; i <= n; i++)
11.        {
12.            Console.Write("number{0}=",i);
13.            double number = double.Parse(Console.ReadLine());
14.            sum += number;
15.        }
16.        Console.WriteLine("Sum={0}",sum);
17.    }
18.}

10 fibonachi numbers


6.    {
7.        Console.Write("n=");
8.        int n = int.Parse(Console.ReadLine());
9.        int fiboTemA = 0;
10.        int fiboTempB = 1;
11.        for (int i = 0; i < n; i++)
12.        {
13.            Console.Write(fiboTemA + " ");
14.            int temp = fiboTemA;
15.            fiboTemA = fiboTempB;
16.            fiboTempB = temp + fiboTempB;
17.        }
18.    }


11 Numbers in Interval Dividable by Given Number

5.    static void Main()
6.    {
7.        Console.Write("Start= ");
8.        int a = int.Parse(Console.ReadLine());
9.        Console.Write("Stop= ");
10.        int b = int.Parse(Console.ReadLine());
11.        for (int i = a; i <= b; i++)
12.        {
13.            if (i % 5 == 0)
14.            {
15.                Console.Write(i);
16.                if (i < b - 2)
17.                {
18.                    Console.Write(",");
19.                }
20.           }
21.
22.        }

Conditional Statements//////////////////////////////////////////////////////////////////////////////////////////////////


2 BonusScore
4.{
5.    static void Main ()
6.    {
7.        Console.Write("Please, enter a whole number in the range [1 ... 9], SCORE = ");
8.        string inputStr = Console.ReadLine();
9.        int score = int.Parse(inputStr);
10.
11.        if (score > 0 && score < 10)
12.        {
13.            if (score >= 1 && score <= 3)
14.            {
15.                Console.WriteLine("Your Final Score is: {0} !", (score * 10));
16.            }
17.            else if (score >= 4 && score <= 6)
18.            {
19.                Console.WriteLine("Your Final Score is: {0} !", (score * 100));
20.            }
21            else
22.            {
23.                Console.WriteLine("Your Final Score is: {0} !", (score * 1000));
24.            }
25.        }
26.        else
27.        {
28.            Console.WriteLine("Input Error - Invalid score !!!");
29.        }
30.        Console.ReadLine();
31.    }


3

class CheckForAPlayCard
4.{
5.    static void Main ()
6.    {
7.        Console.Write("Please, enter a character for a sign your play card, CARD: ");
8.        string card = Console.ReadLine();
9.        string answer;
10.        switch (card)
11.        {
12.            case "2":
13.            case "3":
14.            case "4":
15.            case "5":
16.            case "6":
17.            case "7":
18.            case "8":
19.            case "9":
20.            case "10":
21.            case "J":
22.            case "Q":
23.            case "K":
24.            case "A":
25.                answer = "Yes";
26.                break;
27.            default:
28.                answer = "No";
29.                break;
30.        }
31.        Console.WriteLine("That card is a valid Play Card: \"{0}\" !", answer);
32.        Console.ReadLine();
33.    }


4
4  class MultiplicationSign
4.{
5.    static void Main ()
6.    {
7.        Console.Write("Please, enter the First real number, A = ");
8.        string numberStr = Console.ReadLine();
9.        decimal numA = decimal.Parse(numberStr);
10.        Console.Write("Enter the Second real number, B = ");
11.        numberStr = Console.ReadLine();
12.        decimal numB = decimal.Parse(numberStr);
13.        Console.Write("Enter the Third real number, C = ");
14.        numberStr = Console.ReadLine();
15.        decimal numC = decimal.Parse(numberStr);
16.
17.        char signNum;
18.        if (numA != 0 && numB != 0 && numC != 0)
19.        {
20.            if ((numA > 0 && numB > 0 && numC > 0) || (numA > 0 && numB < 0 && numC < 0)
21.                || (numA < 0 && numB > 0 && numC < 0) || (numA < 0 && numB < 0 && numC > 0))
22.            {
23.                signNum = '+';
24.            }
25.            else
26.            {
27.                signNum = '-';
28.            }
29.        }
30.        else
31.        {
32.            signNum = '0';
33.        }
34.        Console.WriteLine("The Sign of Multiplication of these 3 numbers is: SIGN = {0} !",
35.            signNum);
36.        Console.ReadLine();
37.    }


5

5 class TheBiggestOf3Numbers
4.{
5.    static void Main ()
6.    {
7.        Console.Write("Please, enter the First number, A = ");
8.        string numberStr = Console.ReadLine();
9.        decimal numA = decimal.Parse(numberStr);
10.        Console.Write("Enter the Second number, B = ");
11.        numberStr = Console.ReadLine();
12.        decimal numB = decimal.Parse(numberStr);
13.        Console.Write("Enter the Third number, C = ");
14.        numberStr = Console.ReadLine();
15.        decimal numC = decimal.Parse(numberStr);
16.
17.        decimal theBiggest;
18.        if (numA >= numB)
19.        {
20.            if (numA >= numC)
21.            {
22.                theBiggest = numA;
23.            }
24.            else
25.            {
26.                theBiggest = numC;
27.            }
28.        }
29.        else
30.        {
31.            if (numB >= numC)
32.            {
33.                theBiggest = numB;
34.            }
35.            else
36.            {
37.                theBiggest = numC;
38.            }
39.        }
40.        Console.WriteLine("The Biggest from these 3 numbers is THE BIGGEST = {0} !",
41.            theBiggest);
42.        Console.ReadLine();
43.    }


6


6  class TheBiggestOfFiveNumbers
4.{
5.    static void Main ()
6    {
7.        Console.Write("Please, enter the First number, A = ");
8.        string numberStr = Console.ReadLine();
9.        decimal numA = decimal.Parse(numberStr);
10.        Console.Write("Enter the Second number, B = ");
11.        numberStr = Console.ReadLine();
12.        decimal numB = decimal.Parse(numberStr);
13.        Console.Write("Enter the next number, C = ");
14.        numberStr = Console.ReadLine();
15.        decimal numC = decimal.Parse(numberStr);
16.        Console.Write("Enter the next number, D = ");
17.        numberStr = Console.ReadLine();
18.        decimal numD = decimal.Parse(numberStr);
19.        Console.Write("Enter the next number, E = ");
20.        numberStr = Console.ReadLine();
21.        decimal numE = decimal.Parse(numberStr);
22.
23.        decimal theBiggest;
24.        if (numA >= numB)
25.        {
26.            theBiggest = numA;
27.        }
28.        else
29.        {
30.            theBiggest = numB;
31.        }
32.        if (numC >= theBiggest)
33.        {
34.            theBiggest = numC;
35.        }
36.        if (numD >= theBiggest)
37.        {
38.            theBiggest = numD;
39.        }
40.        if (numE >= theBiggest)
41.        {
42.            theBiggest = numE;
43.        }
44.        Console.WriteLine("The Biggest from these 5 numbers is THE BIGGEST = {0} !",
45.            theBiggest);
46.        Console.ReadLine();
47.    }
48.}


7


7 class Sort3NumbersWithNestedIfs

4.{
5.    static void Main ()
6.    {
7.        Console.Write("Please, enter the First real number, A = ");
8.        string numberStr = Console.ReadLine();
9.        decimal numA = decimal.Parse(numberStr);
10.        Console.Write("Enter the Second real number, B = ");
11.        numberStr = Console.ReadLine();
12.        decimal numB = decimal.Parse(numberStr);
13.        Console.Write("Enter the Third real number, C = ");
14.        numberStr = Console.ReadLine();
15.        decimal numC = decimal.Parse(numberStr);
16.
17.        decimal theBiggest = 0;
18.        decimal theMiddle = 0;
19.        decimal theSmallest = 0;
20.        if (numA >= numC && numB >= numC)
21.        {
22.            theSmallest = numC;
23.            if (numA >= numB)
24.            {
25.                theBiggest = numA;
26.                theMiddle = numB;
27.            }
28.            else
29.            {
30.                theBiggest = numB;
31.                theMiddle = numA;
32.            }
33.        }
34.        else if (numA >= numB && numB <= numC)
35.        {
36.            theSmallest = numB;
37.            if (numA >= numC)
38.            {
39.                theBiggest = numA;
40.                theMiddle = numC;
41.            }
42.            else
43.            {
44.                theBiggest = numC;
45.                theMiddle = numA;
46.            }
47.        }
48.        else
49.        {
50.            theSmallest = numA;
51.            if (numB >= numC)
52.            {
53.                theBiggest = numB;
54.                theMiddle = numC;
55.            }
56.            else
57.            {
58.                theBiggest = numC;
59.                theMiddle = numB;
60.            }
61.        }
62.        Console.WriteLine("These 3 numbers, sorted in Descending order are: {0}, {1}, {2} !",
63.            theBiggest, theMiddle, theSmallest);
64.        Console.ReadLine();
65.    }
66.}


8


 8 nclass DigitAsWord
4.{
5.    static void Main ()
6.    {
7.        Console.Write("Please, enter a one digit number (0-9), DIGIT = ");
8.        string digit = Console.ReadLine();
9.        string result;
10.        switch (digit)
11.        {
12.            case "0":
13.                result = "ZERO";
14.                break;
15.            case "1":
16.                result = "ONE";
17.                break;
18.            case "2":
19.                result = "TWO";
20.                break;
21.            case "3":
22.                result = "THREE";
23.                break;
24.            case "4":
25.                result = "FOUR";
26.                break;
27.            case "5":
28.                result = "FIVE";
29.                break;
30.            case "6":
31.                result = "SIX";
32.                break;
33.            case "7":
34.                result = "SEVEN";
35.                break;
36.            case "8":
37.                result = "EIGHT";
38.                break;
39.            case "9":
40.                result = "NINE";
41.                break;
42.            default:
43.                result = "Not a digit !";
44.                break;
45.        }
46.        Console.WriteLine("That digit is - {0} ", result);
47.        Console.ReadLine();
48.    }


10


10  BeerTime

2.using System.Threading;
3.using System.Globalization;
4.
5.class BeerTime
6.{
7.    static void Main ()
8.    {
9.        Thread.CurrentThread.CurrentCulture = CultureInfo.InvariantCulture;
10.        Console.Write(@"Please, enter your time in format ""hh:mm TT"",
11.(example 05:30 PM),  YOUR TIME = ");
12.        string timeStr = Console.ReadLine();
13.        DateTime customTime;
14.        if (DateTime.TryParse(timeStr, out customTime))
15.            Console.WriteLine("Converted '{0}' to {1} ({2}).", timeStr, customTime,
16.                              customTime.Kind);
17.        else
18.        {
19.            Console.WriteLine("'{0}' is not in an acceptable format.", timeStr);
20.            Console.WriteLine("Error - Invalid Time !!!");
21.            Console.ReadLine();
22.            return;
23.        }
24.
25.        DateTime startBeerTime = DateTime.Parse("01:00 PM");
26.        DateTime endBeerTime = DateTime.Parse("03:00 AM");
27.        if ((customTime >= endBeerTime) && (customTime < startBeerTime))
28.        {
29.            Console.WriteLine("Now is NON-BEER TIME !");
30.        }
31.        else
32.        {
33.            Console.WriteLine("Now is BEER TIME !");
34.        }
35.        Console.ReadLine();
36.    }
37.}


FOR LOOP //////////////////////////////////////////////////////////////////////////


2 class NumbersNotDivisibleBy3And7/////



8.        int number = int.Parse(Console.ReadLine());
9.
10.        for (int i = 1; i <= number; i++)
11.        {
12.            if (i % 3 == 0 || i % 7 == 0)
13.            {
14.                continue;
15.            }
16.            else
17.            {
18.                Console.Write(i + " ");
19.            }
20.        }
21.
22.        Console.WriteLine();


Problem 3.  Min, Max, Sum and Average of N Numbers


8.  int length = int.Parse(Console.ReadLine());
9.
10.        int min = int.MaxValue;
11.        int max = int.MinValue;
12.        double sum = 0;
13.        double avg = 0;
14.
15.        for (int i = 0; i < length; i++)
16.        {
17.            int number = int.Parse(Console.ReadLine());
18.
19.            //min
20.            min = Math.Min(min, number);
21.
22.            //max
23.            max = Math.Max(max, number);
24.
25.            //sum
26.            sum += number;
27.
28.            //avg
29.            avg = sum / length;
30.        }
31.
32.        Console.WriteLine("Min = " + min);
33.        Console.WriteLine("Max = " + max);
34.        Console.WriteLine("Sum = " + sum);
35.        Console.WriteLine("Avg = {0:F2}", avg);
36.    }


Problem 4.  Print a Deck of 52 Cards


string[] cards = { "2", "3", "4", "5", "6", "7", "8", "9", "10", "J", "Q", "K", "A" };
8.        int[] colors = { 3, 4, 5, 6 };
9.
10.        foreach (var card in cards)
11.        {
12.            foreach (var color in colors)
13.            {
14.                Console.Write(card);
15.                Console.Write((char)color + " ");
16.            }
17.
18.            Console.WriteLine();



Problem 5.  Calculate 1 + 1!/X + 2!/X2 + … + N!/XN

7.          Console.Write("n = ");
8.        int n = int.Parse(Console.ReadLine());
9.        Console.Write("x = ");
10.        int x = int.Parse(Console.ReadLine());
11.
12.        double factN = 1;
13.        double multiX = 1;
14.        double result = 1;
15.
16.        for (int i = 1; i <= n; i++)
17.        {
18.            factN *= i;
19.            multiX *= x;
20.            result += factN / multiX;
21.        }
22.
23.        Console.WriteLine("{0:F5}", result);
24.    }


Problem 6.  Calculate N! / K!

8.        Console.Write("n = ");
9.        int n = int.Parse(Console.ReadLine());
10.        Console.Write("k = ");
11.        int k = int.Parse(Console.ReadLine());
12.
13.        if (n > 1 && k > 1 && n < 100 && k < 100)
14.        {
15.            BigInteger factN = 1;
16.            BigInteger factK = 1;
17.            BigInteger result = 0;
18.
19.            for (int i = 1; i <= n; i++)
20.            {
21.                factN *= i;
22.            }
23.
24.            for (int j = 1; j <= k; j++)
25.            {
26.                factK *= j;
27.            }
28.
29.            result = factN / factK;
30.
31.            Console.WriteLine(result);
32.        }
33.        else
34.        {
35.            Console.WriteLine("Invalid input!");
36.        }



        7 Problem 7.    Calculate N! / (K! * (N-K)!)


5.{
6.    static void Main()
7.    {
8.        Console.Write("n = ");
9.        int n = int.Parse(Console.ReadLine());
10.        Console.Write("k = ");
11.        int k = int.Parse(Console.ReadLine());
12.
13.        if (n > 1 && k > 1 && n < 100 && k < 100)
14.        {
15.            BigInteger factN = 1;
16.            BigInteger factK = 1;
17.            BigInteger factNAndK = 1;
18.            BigInteger result = 0;
19.
20.            for (int i = 1; i <= n; i++)
21.            {
22.                factN *= i;
23.            }
24.
25.            for (int j = 1; j <= k; j++)
26.            {
27.                factK *= j;
28.            }
29.
30.            for (int z = 1; z <= n - k; z++)
31.            {
32.                factNAndK *= z;
33.            }
34.
35.            result = factN / (factK * factNAndK);
36.
37.            Console.WriteLine(result);
38.        }
39.        else
40.        {
41.            Console.WriteLine("Invalid input!");
42.        }



Problem 8.  Catalan Numbers

8.        Console.Write("n = ");
9.        int n = int.Parse(Console.ReadLine());
10.
11.        if (n > 1 && n < 100)
12.        {
13.            BigInteger multiFactN = 1;
14.            BigInteger plusFactN = 1;
15.            BigInteger factN = 1;
16.            BigInteger result = 0;
17.
18.            for (int i = 1; i <= 2 * n; i++)
19.            {
20.                multiFactN *= i;
21.            }
22.
23.            for (int j = 1; j <= n + 1; j++)
24.            {
25.                plusFactN *= j;
26.            }
27.
28.            for (int k = 1; k <= n; k++)
29.            {
30.                factN *= k;
31.            }
32.
33.            result = multiFactN / (plusFactN * factN);
34.
35.            Console.WriteLine(result);
36.        }
37.        else
38.        {
39.            Console.WriteLine("Invalid input!");
40.        }



Problem 9.  Matrix of Numbers

7.        Console.Write("n = ");
8.        int n = int.Parse(Console.ReadLine());
9.
10.        if (n > 1 && n < 20)
11.        {
12.            for (int i = 0; i < n; i++)
13.            {
14.                for (int j = i + 1; j <= n + i; j++)
15.                {
16.                    Console.Write(j + " ");
17.                }
18.
19.                Console.WriteLine();
20.            }
21.        }
22.        else
23.        {
24.            Console.WriteLine("Invalid input!");
25.        }




Problem 10. Odd and Even Product

7.          int even = 1;
8.        int odd = 1;
9.
10.        string readNumbers = Console.ReadLine();
11.        string[] numbers = readNumbers.Split(new char[] { ' ' }, StringSplitOptions.RemoveEmptyEntries);
12.
13.        for (int i = 0; i < numbers.Length; i++)
14.        {
15.            int number = int.Parse(numbers[i]);
16.
17.            if (i % 2 == 0)
18.            {
19.                even *= number;
20.            }
21.            else
22.            {
23.                odd *= number;
24.            }
25.        }
26.
27.        if (even == odd)
28.        {
29.            Console.WriteLine("yes");
30.            Console.WriteLine("product = " + even);
31.        }
32.        else
33.        {
34.            Console.WriteLine("no");
35.            Console.WriteLine("odd_product = " + odd);
36.            Console.WriteLine("even_product = " + even);
37.        }



Problem 11. Random Numbers in Given Range

7.        Console.Write("n = ");
8.        int n = int.Parse(Console.ReadLine());
9.        Console.Write("min = ");
10.        int min = int.Parse(Console.ReadLine());
11.        Console.Write("max = ");
12.        int max = int.Parse(Console.ReadLine());
13.
14.        if (min <= max)
15.        {
16.            Random random = new Random();
17.
18.            for (int i = 0; i < n; i++)
19.            {
20.                Console.Write(random.Next(min, max + 1) + " ");
21.            }
22.
23.            Console.WriteLine();
24.        }


Problem 12. * Randomize the Numbers 1…N

7.        Console.Write("n = ");
8.        int n = int.Parse(Console.ReadLine());
9.
10.        Random randomNumbers = new Random();
11.
12.        for (int i = 1; i <= n; i++)
13.        {
14.            Console.Write(randomNumbers.Next(1, n + 1) + " ");
15.        }
16.
17.        Console.WriteLine();