Условия и решения на задачите от лекция „Conditional Statements“
Задача 1. Compare Two Integers
Условие: Write an if statement that examines two integer variables and exchanges their values if the first one is greater than the second one.
Решение:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace _1.CompareTwoInteger
{
class Program
{
static void Main()
{
int a, b, c;
Console.Write("Enter the first number a:");
bool isaInt = int.TryParse(Console.ReadLine(),out a);
Console.Write("Enter the second number b:");
bool isbInt = int.TryParse(Console.ReadLine(),out b);
if (isaInt && isbInt)
{
if (a > b)
{
c = a;
a = b;
b = c;
}
Console.WriteLine("a={0}",a);
Console.WriteLine("b={0}",b);
}
else
{
Console.WriteLine("Not a valid entry! Some of the values are not integer!");
}
}
}
}
Задача 2. Show The Sign Of The Product
Условие: Write a program that shows the sign (+ or -) of the product of three real numbers without calculating it. Use a sequence of if statements.
Решение:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Globalization;
namespace _2.ShowTheSignOfTheProduct
{
class Program
{
static void Main()
{
Thread.CurrentThread.CurrentCulture = CultureInfo.InvariantCulture;
double a, b, c;
byte positiveNumbers=0;
Console.Write("Enter the first number a:");
bool isaDouble = double.TryParse(Console.ReadLine(), out a);
Console.Write("Enter the second number b:");
bool isbDouble = double.TryParse(Console.ReadLine(), out b);
Console.Write("Enter the third number c:");
bool iscDouble = double.TryParse(Console.ReadLine(), out c);
if (isaDouble && isbDouble && iscDouble)
{
if (Math.Sign(a) == 1)
{
positiveNumbers=(byte)(positiveNumbers + 1);
}
if (Math.Sign(b) == 1)
{
positiveNumbers = (byte)(positiveNumbers + 1);
}
if (Math.Sign(c) == 1)
{
positiveNumbers = (byte)(positiveNumbers + 1);
}
if (positiveNumbers % 2 == 0)
{
Console.WriteLine("The sign of the product is (-)");
}
else
{
Console.WriteLine("The sign of the product is (+)");
}
}
else
{
Console.WriteLine("Not a valid entry! Some of the values are not double!");
}
}
}
}
Задача 3. Find The Biggest Number Of Three
Условие: Write a program that finds the biggest of three integers using nested if statements.
Решение:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace _3.FindTheBiggestNumberOfThree
{
class Program
{
static void Main()
{
int a, b, c,biggestNumber;
Console.Write("Enter the first number a:");
bool isaInt = int.TryParse(Console.ReadLine(), out a);
Console.Write("Enter the second number b:");
bool isbInt = int.TryParse(Console.ReadLine(), out b);
Console.Write("Enter the third number c:");
bool iscInt = int.TryParse(Console.ReadLine(), out c);
if (isaInt && isbInt && iscInt)
{
if (a > b)
{
if (b > c)
{
biggestNumber = a;
}
else
{
if (c > a)
{
biggestNumber = c;
}
else
{
biggestNumber = a;
}
}
}
else
{
if (a > c)
{
biggestNumber = b;
}
else
{
if (c > b)
{
biggestNumber = c;
}
else
{
biggestNumber = b;
}
}
}
Console.WriteLine("The biggest number={0}", biggestNumber);
}
else
{
Console.WriteLine("Not a valid entry! Some of the values are not integer!");
}
}
Задача 4. Sort 3 Real Numbers
Условие: Sort 3 real values in descending order using nested if statements.
Решение:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Globalization;
namespace _4.Sort3RealNumbers
{
class Program
{
static void Main()
{
Thread.CurrentThread.CurrentCulture = CultureInfo.InvariantCulture;
double a, b, c;
double[] array={0,0,0};
Console.Write("Enter the first number a:");
bool isaDouble = double.TryParse(Console.ReadLine(), out a);
Console.Write("Enter the second number b:");
bool isbDouble = double.TryParse(Console.ReadLine(), out b);
Console.Write("Enter the third number c:");
bool iscDouble = double.TryParse(Console.ReadLine(), out c);
if (isaDouble && isbDouble && iscDouble)
{
if (a > b)
{
if (b > c)
{
array[0] = a;
array[1] = b;
array[2] = c;
}
else
{
if (c > a)
{
array[0] = c;
array[1] = a;
array[2] = b;
}
else
{
array[0] = a;
array[1] = c;
array[2] = b;
}
}
}
else
{
if (a > c)
{
array[0] = b;
array[1] = a;
array[2] = c;
}
else
{
if (c > b)
{
array[0] = c;
array[1] = b;
array[2] = a;
}
else
{
array[0] = b;
array[1] = c;
array[2] = a;
}
}
}
Console.WriteLine("The descending order is {0};{1};{2}", array[0],array[1],array[2]);
}
else
{
Console.WriteLine("Not a valid entry! Some of the values are not integer!");
}
}
}
}
Задача 5. Print Name Of The Digit
Условие: Write program that asks for a digit and depending on the input shows the name of that digit (in English) using a switch statement.
Решение:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace _5.PrintNameOfTheDigit
{
class Program
{
static void Main()
{
byte digit;
Console.Write("Enter the digit:");
bool isDigit = byte.TryParse(Console.ReadLine(), out digit);
if (isDigit)
{
switch (digit)
{
case 0: Console.WriteLine("zero"); break;
case 1: Console.WriteLine("one"); break;
case 2: Console.WriteLine("two"); break;
case 3: Console.WriteLine("three"); break;
case 4: Console.WriteLine("four"); break;
case 5: Console.WriteLine("five"); break;
case 6: Console.WriteLine("six"); break;
case 7: Console.WriteLine("seven"); break;
case 8: Console.WriteLine("eight"); break;
case 9: Console.WriteLine("nine"); break;
default: Console.WriteLine("This is not one digit entry!"); break;
}
}
else
{
Console.WriteLine("Not a valid entry! This is not one digit entry!");
}
}
}
}
Задача 6. Qadratic Equation
Условие: Write a program that enters the coefficients a, b and c of a quadratic equation a*x2 + b*x + c = 0 and calculates and prints its real roots. Note that quadratic equations may have 0, 1 or 2 real roots.
Решение:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Globalization;
namespace _6.QadraticEquation
{
class Program
{
static void Main()
{
Thread.CurrentThread.CurrentCulture = CultureInfo.InvariantCulture;
double a, b, c, discriminant, x1, x2;
Console.Write("Enter the first coefficient a:");
bool isaDouble = double.TryParse(Console.ReadLine(), out a);
Console.Write("Enter the second coefficients b:");
bool isbDouble = double.TryParse(Console.ReadLine(), out b);
Console.Write("Enter the third coefficients c:");
bool iscDouble = double.TryParse(Console.ReadLine(), out c);
if (isaDouble && isbDouble && iscDouble)
{
discriminant = b * b - 4 * a * c;
if (discriminant > 0)
{
x1 = (-b + Math.Sqrt(discriminant)) / 2 * a;
x2 = (b + Math.Sqrt(discriminant)) / 2 * a;
Console.WriteLine("The real roots are:");
Console.WriteLine("x1={0}", x1);
Console.WriteLine("x2={0}", x2);
}
else if (discriminant == 0)
{
x1 = x2 = -b / 2 * a;
Console.WriteLine("The real roots are:");
Console.WriteLine("x1={0}", x1);
Console.WriteLine("x2={0}", x2);
}
else
{
Console.WriteLine("There are no real roots!");
}
}
else
{
Console.WriteLine("Not a valid entry! Some of the numbers are not double!");
}
}
}
}
Задача 7. Find The Greatest From 5 Variables
Условие: Write a program that finds the greatest of given 5 variables.
Решение:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Globalization;
namespace _7.FindTheGreatestFrom5Variables
{
class Program
{
static void Main()
{
Thread.CurrentThread.CurrentCulture = CultureInfo.InvariantCulture;
double[] array={0,0,0,0,0};
bool isNumber=true;
double greatest=double.MinValue;
for (int i = 0; i < 5; i++) { Console.Write("Enter the {0} variable:",i+1); isNumber = double.TryParse(Console.ReadLine(), out array[i]); if(isNumber==false) { Console.WriteLine("Not a valid entry! This is not a number entry!"); break; } else { if(array[i] > greatest)
{
greatest = array[i];
}
}
}
if (isNumber)
{
Console.WriteLine("The greatest number = {0}", greatest);
}
}
}
}
Задача 8. Int Double Or String Conversion
Условие: Write a program that, depending on the user’s choice inputs int, double or string variable. If the variable is integer or double, increases it with 1. If the variable is string, appends „*“ at its end. The program must show the value of that variable as a console output. Use switch statement.
Решение:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Globalization;
namespace _8.IntDoubleOrStringConversion
{
class Program
{
static void Main()
{
Thread.CurrentThread.CurrentCulture = CultureInfo.InvariantCulture;
double doubleNumber=0;
int intNumber=0;
string stringInput;
byte entryType;
Console.Write("Please do the data entry:");
stringInput = Console.ReadLine();
bool isDouble = double.TryParse(stringInput,out doubleNumber);
if (isDouble)
{
if (doubleNumber % 1 == 0)
{
intNumber = (int)doubleNumber;
entryType = 1;//Integer entry
}
else
{
entryType = 2;//Double entry
}
}
else
{
entryType = 3;//String entry
}
switch (entryType)
{
case 1: Console.WriteLine("Integer input. The output is:{0}", intNumber + 1); break;
case 2: Console.WriteLine("Double input. The output is:{0}", doubleNumber + 1); break;
case 3: Console.WriteLine("String input. The output is:{0}", stringInput + "*"); break;
}
}
}
}
Задача 9. Check If The Sum Of Subset Is 0
Условие: We are given 5 integer numbers. Write a program that checks if the sum of some subset of them is 0. Example: 3, -2, 1, 1, 8 => 1+1-2=0.
Решение:
using System;
using System.Collections.Generic;
namespace _9.CheckIfTheSumOfSubsetIs0
{
class Program
{
static void Main()
{
bool isInt=true;
bool isElementZero=false;
int[] intNumbers=new int[5];
Console.Write("Enter a sequence of five integers delimited with \",\":");
string[] strNumbers =(Console.ReadLine()).Split(',');
if (strNumbers.Length == 5)
{
for (int i = 0; i < 5; i++)
{
isInt = int.TryParse(strNumbers[i], out intNumbers[i]);
if (isInt == false)
{
break;
}
if (intNumbers[i]==0)
{
isElementZero = true;
}
}
if (isInt)
{
if (isElementZero)
{
Console.WriteLine("There is a subset with sum equal to 0");
}
else
{
switch (FindZeroSum(intNumbers))
{
case true: Console.WriteLine("There is a subset with sum equal to 0"); break;
case false: Console.WriteLine("There is no subset with sum equal to 0"); break;
}
}
}
else
{
Console.WriteLine("Wrong entry! Some of the numbers are not integer!");
}
}
else
{
Console.WriteLine("Wrong entry! The members of the sequence are less or more than 5!");
}
}
private static bool FindZeroSum(int[] numbers)
{
int[] dynamicSums = new int[32];
for (int i = 1; i < 5; i++)// numbers in the array
{
int j, k;
for (j = 0; j < ((1 << i) - (i + 1)); j++)// the sum with already summed elements
{
if ((dynamicSums[(1 << i) - (i + 1) + j] = numbers[i] + dynamicSums[j]) == 0)
{
return true;
}
}
for (k = 0; k < i; k++)// the sums with the new elements
{
if ((dynamicSums[(1 << i) - (i + 1) + (j + k)] = numbers[k] + numbers[i]) == 0)
{
return true;
}
}
}
return false;
}
}
}
Задача 10. Bonus Scores
Условие: Write a program that applies bonus scores to given scores in the range [1..9]. The program reads a digit as an input. If the digit is between 1 and 3, the program multiplies it by 10; if it is between 4 and 6, multiplies it by 100; if it is between 7 and 9, multiplies it by 1000. If it is zero or if the value is not a digit, the program must report an error.
Use a switch statement and at the end print the calculated new value in the console.
Решение:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace _10.BonusScores
{
class Program
{
static void Main()
{
int n;
Console.Write("Enter a digit in the range of [1-9]:");
bool isnInt = int.TryParse(Console.ReadLine(),out n);
if (isnInt && n > 0 && n < 10)
{
switch (n)
{
case (1): n = n * 10; break;
case (2): n = n * 10; break;
case (3): n = n * 10; break;
case (4): n = n * 100; break;
case (5): n = n * 100; break;
case (6): n = n * 100; break;
case (7): n = n * 1000; break;
case (8): n = n * 1000; break;
case (9): n = n * 1000; break;
}
Console.WriteLine(n);
}
else
{
Console.WriteLine("Not a valid entry!");
}
}
}
}
Задача 11. Number To Text Converter
Условие: Write a program that converts a number in the range [0…999] to a text corresponding to its English pronunciation. Examples:
0 => „Zero“
273 => „Two hundred seventy three“
400 => „Four hundred“
501 => „Five hundred and one“
711 => „Seven hundred and eleven“
Решение:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace _11.NumberToTextConverter
{
class Program
{
static void Main(string[] args)
{
int number;
bool isNumberInt;
string[,] numbers ={
{"one","two","three","four","five","six","seven","eight","nine"},
{"eleven","twelve","thirteen","fourteen","fifteen","sixteen","seventeen","eighteen","nineteen"},
{"ten","twenty","thirty","fourty","fifty","sixty","seventy","eighty","ninety"},
};
Console.WriteLine("Enter the number:");
isNumberInt = int.TryParse(Console.ReadLine(), out number);
if (isNumberInt && number > -1 && number < 1000) { if (number / 100 > 0)//Are there any hundreds?
{
Console.Write("{0} hundred ", numbers[0, (number / 100) - 1]);
if ((number % 100) / 10 > 0)//Are there any tens?
{
Console.Write("and ");
if ((number % 100) / 10 == 1 && (number % 100) % 10 > 0)//Are the tens between 10 and 20?
{
Console.WriteLine(numbers[1, ((number % 100) % 10) - 1]);
}
else
{
Console.Write(numbers[2, ((number % 100) / 10) - 1]);
if ((number % 100) % 10 > 0)//Are there any units?
{
Console.WriteLine(" {0}", numbers[0, ((number % 100) % 10) - 1]);
}
else
{
Console.WriteLine();
}
}
}
else if (((number % 100) % 10) > 0)//Are there any units?
{
Console.Write("and ");
Console.WriteLine(numbers[0, ((number % 100) % 10) - 1]);
}
else
{
Console.WriteLine();
}
}
else if (number / 10 > 0 && number / 10 < 10)//Are there only tens and units? { if (number / 10 == 1 && number % 10 > 0)//Are the tens between 10 and 20?
{
Console.WriteLine(numbers[1, ((number % 100) % 10) - 1]);
}
else
{
Console.Write(numbers[2, (number / 10) - 1]);
if (number % 10 > 0)
{
Console.WriteLine(" {0}", numbers[0, ((number % 100) % 10) - 1]);
}
else
{
Console.WriteLine();
}
}
}
else if (number == 0)//Is the number 0?
{
Console.WriteLine("zero");
}
else//Are there only units?
{
Console.WriteLine(numbers[0, number - 1]);
}
}
else
{
Console.WriteLine("Not a valid entry!");
}
}
}
}