Katas Notes

katas-notes.md

Kata Practice

Sum of all multiples of 3 or 5

Given an integer, write a function findSum that returns the sum of all multiples of 3 or 5 up to up to n.

findSum(8) returns 5 findSum(33) returns 10

JavaScript

Simple

function findSum(n) {
  let sum = 0;
  for (let i=0; i<=n; i++) {
    if (i%3==0 || i%5==0) sum += i;
  }
  return sum;
}

Functional

const findSum = (n) => (
  Array.from({ length: n+1}, (v,i) => i)
    .filter(o => (o%3==0) || (o%5==0))
    .reduce((a, b) => a+b)
);

C# 1 Basic, Basic + List

namespace Solution
{
  public static class Program
  {
    public static int findSum(int n)
    {
      int sum = 0;
      for(var i=0; i<=n; i++) {
        if (i % 3 == 0 || i % 5 == 0) sum += i;
      }
      return sum;
    }
  }
}

using System.Collections.Generic;

namespace Solution
{
  public static class Program
  {
    public static int findSum(int n)
    {
      List<int> found = new List<int>();
      for(var i=0; i<=n; i++) {
        if (i % 3 == 0 || i % 5 == 0) {
          found.Add(i);
        }
      }
      
      int sum=0;
      foreach (var num in found) {
        sum += num;
      }
      return sum;
    }
  }
}

C# 2: Using LINQ:Sum

using System.Collections.Generic;
using System.Linq;

namespace Solution
{
  public static class Program
  {
    public static int findSum(int n)
    {
      List<int> found = new List<int>();
      for(var i=0; i<=n; i++) {
        if (i % 3 == 0 || i % 5 == 0) {
          found.Add(i);
        }
      }
      return found.Sum();
    }
  }
}

C# 3: using LINQ:Aggregate / Where

using System.Collections.Generic;
using System.Linq;
using System;

namespace Solution
{
  public static class Program
  {
    public static int findSum(int n)
    {
      var f = Enumerable.Range(1, n)
        .Where( o => (o%3 == 0) || (o%5==0))
        .Aggregate( (a, b) => a+b);
      Console.WriteLine(f);
      return f;
    }
  }
}

Sum of Squares

Write a function findSum(array) that returns the sum of all squares in the array.

findSum([1, 2, 3]) returns 15 findSum([2, 5]) returns 34

JavaScript: Simple

function squareSum(numbers){
  let sum=0;
  for (let val of numbers) sum += val*val;
  return sum;
}

JavaScript: Reduce

function squareSum(numbers){
  return numbers.reduce((a,b) => a+(b*b));
}

C#: Simple

public static class Kata
{
  public static int SquareSum(int[] n)
  { 
    int sum=0;
    foreach (int val in n) {
      sum += val*val;
    }
    return sum;
  }
}

C# LINQ

using System.Linq;

public static class Kata
{
  public static int SquareSum(int[] n)
  { 
    return n.Select(v => v*v).Sum();
  }
}