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Rod D - Problem solving practice exercises #25

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Rod D - Problem solving practice exercises #25

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171 changes: 109 additions & 62 deletions problem-solving/Program.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -15,141 +15,188 @@ static void Main(string[] args)

public static long SumArray(IEnumerable<int> arr)
{
// return the sum of all the values in the array
// TODO
return 0;
return arr.Select(n => (long)n).Sum();
}

public static long SumArrayOddValues(IEnumerable<int> arr)
{
// return the sum of all the values in the array that are odd
// TODO
return 0;
return arr.Where(number => number % 2 != 0).Select(n => (long)n).Sum();
}

public static long SumArrayEverySecondValue(IEnumerable<int> arr)
{
// return the sum of every second value in the array. i.e. the 2nd value + the 4th value + the 6th value ...
// TODO
return 0;
return arr.Where((number, ix) => ix % 2 != 0).Sum();
}

public static IEnumerable<int> GetUniqueValues(IEnumerable<int> arr)
{
// return an array that contains only unique values from the passed in array
// TODO
return null;
return arr.Distinct();
}

public static IEnumerable<int> GetArrayIntersect(IEnumerable<int> arrA, IEnumerable<int> arrB)
{
// return an array that contains all the values that are in array A and array B
// TODO
return null;
return arrA.Distinct().Where(number => arrB.Contains(number));
}

public static IEnumerable<int> GetArrayNotIntersect(IEnumerable<int> arrA, IEnumerable<int> arrB)
{
// return an array that contains all the values that are in array A or array B but not in both array A and array B
// TODO
return null;
return arrA.Except(arrB).Concat(arrB.Except(arrA));
}

public static Boolean HasSum(IEnumerable<int> arr, long target)
{
// return true if any 2 values in the array have a sum equal to the target value
// TODO
var set = new HashSet<int>();
foreach (int number in arr)
{
if(set.Contains((int)target-number))
{
return true;
}
set.Add(number);
}
return false;
}

public static long LoneSum(IEnumerable<int> arr)
{
// Given an array of int values, return their sum.
// However, if any of the values is the same as another of the values, it does not count towards the sum.
return 0;
if (arr == null) throw new ArgumentNullException();

var addedNums = new HashSet<int>();
var duplicates = new HashSet<int>();
int sum = 0;
foreach (int number in arr)
{
if(!addedNums.Contains(number))
{
sum += number;
addedNums.Add(number);
}
else if (!duplicates.Contains(number))
{
duplicates.Add(number);
sum -= number;
}
}
return sum;
}

public static String DoubleString(String s)
{
// return a string that is the original string with each character in the string repeated twice
// e.g. for input "ABCDE", return "AABBCCDDEE"
return null;
if (s == null) throw new ArgumentNullException();

char[] charArray = new char[s.Length*2];
int ix = 0;
foreach (char c in s)
{
charArray[ix++] = c;
charArray[ix++] = c;
}
return new String(charArray);
}

public static int CountChars(String s, char c)
{
// return the count of how many times char c occurs in string s
return 0;
return s.Count(charInString => charInString == c);
}

public static long SumDigits(String s)
{
// return the sum of the digits 0-9 that appear in the string, ignoring all other characters
// e.g. "123" return 6
return 0;
return s.Where(charInString => charInString > '0' && charInString <= '9')
.Select(charVal => charVal - '0')
.Sum();
}

public static long SumNumbers(String s)
{
// return the sum of the numbers that appear in the string, ignoring all other characters
// a number is a series of 1 or more digits in a row
// e.g. "11 22" returns 33
return 0;
String[] numbers = Regex.Split(s, "[^.0-9]");
return numbers.Where(stringVal => stringVal != "")
.Select(stringVal => Int32.Parse(stringVal))
.Sum();
}

public static Boolean IsAnagram(String s1, String s2)
{
// return true if String s1 is an anagram of s2, otherwise return false
// An anagram is produced by rearranging the letters of one string into another
// e.g. care is an anagram of race
// cat is not an anagram of rat
return false;
if (s1.Length != s2.Length) return false;
foreach(char s1Char in s1)
{
int matchingIx = s2.IndexOf(s1Char);
if (matchingIx < 0)
{
return false;
}
else
{
s2 = s2.Remove(matchingIx, 1);
}
}
return true;
}

public static int BlackJack(int count1, int count2)
{
// Given 2 integer values greater than 0,
// return whichever value is nearest to 21 without going over.
// Return 0 if they both go over.
return 0;
var counts = new List<int>();
counts.Add(count1);
counts.Add(count2);
return NPlayerBlackJack(counts);
}

public static int FivePlayerBlackJack(int count1, int count2, int count3, int count4, int count5)
{
// Given 5 integer values greater than 0,
// return whichever value is nearest to 21 without going over.
// Return 0 if they all go over.
return 0;
var counts = new List<int>();
counts.Add(count1);
counts.Add(count2);
counts.Add(count3);
counts.Add(count4);
counts.Add(count5);
return NPlayerBlackJack(counts);
}

public static int NPlayerBlackJack(IEnumerable<int> counts)
{
// Given a list of integer values greater than 0,
// return whichever value is nearest to 21 without going over.
// Return 0 if they all go over.
return 0;
IEnumerable<int> validHands = counts.Where(val => val <= 21 && val >= 0);

return validHands.Count() > 0 ? validHands.Max() : 0;
}

public static Dictionary<String, int> WordCount(IEnumerable<String> arr)
{
// Given an array of Strings,
// return a dictionary keyed on the string with the count of how many times each string appears in the array
return null;
var dictionary = new Dictionary<String, int>();
foreach(String word in arr)
{
int currentCount;
dictionary.TryGetValue(word, out currentCount);
dictionary[word] = currentCount + 1;
}
return dictionary;
}

public static int Factorial(int n)
{
// Given n, return the factorial of n, which is n * (n-1) * (n-2) ... 1
return 0;
if (n <= 0) return 1;
return n * Factorial(n - 1);
}

public static List<String> FB(int n)
{
// Given n, print the numbers from 1 to n as a string to a List of strings, with the following exceptions:
// If the number is divisable by 3, replace it with the word "Fizz"
// If the number is divisable by 5, replace it with the word "Buzz"
// If the number is divisable by both 3 and 5, replace it with the word "FizzBuzz"
return null;
var output = new List<String>();
for (int i = 1; i <= n; i++)
{
String thisString = "";
if (i % 3 == 0)
{
thisString += "Fizz";
}
if (i % 5 == 0)
{
thisString += "Buzz";
}
if (thisString.Length == 0)
{
thisString = i.ToString();
}
output.Add(thisString);
}
return output;
}
}
}