Homework, lesson 5

koans/AboutApplyingWhatWeHaveLearnt.js

@@ -32,16 +32,21 @@ describe("About Applying What We Have Learnt", function() {
         }
     }
 
-    expect(productsICanEat.length).toBe(FILL_ME_IN);
+    expect(productsICanEat.length).toBe(1);
   });
 
   it("given I'm allergic to nuts and hate mushrooms, it should find a pizza I can eat (functional)", function () {
 
       var productsICanEat = [];
 
       /* solve using filter() & all() / any() */
+      productsICanEat = _(products).filter(function (product) {
+          return !product.containsNuts && !_(product.ingredients).any(function (ingredient) {
+              return ingredient === "mushrooms"
+          });
+      });
 
-      expect(productsICanEat.length).toBe(FILL_ME_IN);
+      expect(productsICanEat.length).toBe(1);
   });
 
   /*********************************************************************************/
@@ -55,14 +60,21 @@ describe("About Applying What We Have Learnt", function() {
       }
     }
 
-    expect(sum).toBe(FILL_ME_IN);
+    expect(sum).toBe(233168);
   });
 
   it("should add all the natural numbers below 1000 that are multiples of 3 or 5 (functional)", function () {
 
-    var sum = FILL_ME_IN;    /* try chaining range() and reduce() */
+      var sum = _(_.range(1, 1000))
+          .chain()
+          .filter(function (num) {
+              return num % 3 === 0 || num % 5 === 0;
+          })
+          .reduce(function (sum, num) {
+              return sum + num;
+          }).value();    /* try chaining range() and reduce() */
 
-    expect(233168).toBe(FILL_ME_IN);
+    expect(233168).toBe(sum);
   });
 
   /*********************************************************************************/
@@ -75,39 +87,167 @@ describe("About Applying What We Have Learnt", function() {
         }
     }
 
-    expect(ingredientCount['mushrooms']).toBe(FILL_ME_IN);
+    expect(ingredientCount['mushrooms']).toBe(2);
   });
 
   it("should count the ingredient occurrence (functional)", function () {
     var ingredientCount = { "{ingredient name}": 0 };
 
     /* chain() together map(), flatten() and reduce() */
-
-    expect(ingredientCount['mushrooms']).toBe(FILL_ME_IN);
+    _(products).chain()
+      .map(function (product) { return product.ingredients;})
+      .flatten()
+      .reduce(function (memo, ingredient) { memo[`${ingredient}`] = (memo[`${ingredient}`] || 0) + 1; return memo},
+          ingredientCount)
+      .value();
+
+    expect(ingredientCount['mushrooms']).toBe(2);
   });
 
-  /*********************************************************************************/
-  /* UNCOMMENT FOR EXTRA CREDIT */
-  /*
   it("should find the largest prime factor of a composite number", function () {
+    function isPrime(number) {
+      for(let i= number-1; i>1; i--){
+          if(number%i===0) return false;
+      }
+      return true;
+    }
 
+    function biggestPrimeFactor(number) {
+      for(let i=number;i>1;i--){
+          if(number%i===0 && isPrime(i)){
+              return i;
+          }
+      }
+      return 1;
+    }
+
+    expect(biggestPrimeFactor(6857)).toBe(6857);
   });
 
   it("should find the largest palindrome made from the product of two 3 digit numbers", function () {
+    function isPoly(number) {
+      let strNumber = `${number}`
+      let coefficient = strNumber.length % 2 === 0 ? 0 : 1;
+      let strNumber1 = strNumber.slice(0, (strNumber.length - coefficient) / 2);
+      let strNumber2 = strNumber
+          .slice((strNumber.length + coefficient) / 2, strNumber.length)
+          .split("")
+          .reverse()
+          .join("");
+      return strNumber1 === strNumber2;
+    }
+
+    function biggestPoly() {
+      let result = 1;
+      for(let i=999;i>99;i--){
+          for(let j=i-1;j>99;j--){
+              if(isPoly(i*j) && result<(i*j)){
+                  result = i*j;
+              }
+          }
+      }
+      return result;
+    }
 
+    expect((biggestPoly())).toBe(906609);
   });
 
   it("should find the smallest number divisible by each of the numbers 1 to 20", function () {
+    function isDividedBy(rangeStart, rangeEnd, number) {
+      let result = true;
+      _(_.range(rangeStart, rangeEnd+1)).forEach(function (factor) {
+          if(number % factor !== 0) {
+              result = false;
+          }
+      });
+      return result;
+    }
 
+    function gcd(number1, number2) {
+      return number2 === 0 ? number1 : gcd(number2, number1%number2);
+    }
+    function lcm(number1, number2) {
+      return number1/gcd(number1, number2)*number2;
+    }
 
+    let expectedNumber = 2;
+    for(let i=2;i<=20;i++){
+      expectedNumber = lcm(expectedNumber, i);
+    }
+
+    expect(isDividedBy(1, 20, expectedNumber)).toBe(true);
   });
 
   it("should find the difference between the sum of the squares and the square of the sums", function () {
+    function diff() {
+      let sumOfSquare = 0;
+      let squareOfSums = 0;
+      for(let i=0; i< arguments.length; i++){
+          sumOfSquare += arguments[i]*arguments[i];
+          squareOfSums += arguments[i];
+      }
+      squareOfSums *= squareOfSums;
+      return squareOfSums-sumOfSquare;
+    }
 
+    function mathDiff(n) {
+      return Math.abs((3*n*n + 2*n)*(1-n*n)/12);
+    }
+
+    expect(diff(1,2,3,4,5)).toBe(mathDiff(5));
   });
 
   it("should find the 10001st prime", function () {
+    function isPrime(number) {
+      for(let i= number-1; i>1; i--){
+          if(number%i===0) return false;
+      }
+      return true;
+    }
+    function prime(limit) {
+      let result = [];
+      let number = 2;
+      while (result.length<limit) {
+          if(isPrime(number)){
+              result.push(number);
+          }
+          number++;
+      }
+      return result;
+    }
+
+    function eratosthenes(n) {
+      // Eratosthenes algorithm to find all primes under n
+      let array = [], upperLimit = Math.sqrt(n), output = [];
+
+      // Make an array from 2 to (n - 1)
+      for (let i = 0; i < n; i++) {
+          array.push(true);
+      }
 
+      // Remove multiples of primes starting from 2, 3, 5,...
+      for (let i = 2; i <= upperLimit; i++) {
+          if (array[i]) {
+              for (let j = i * i; j < n; j += i) {
+                  array[j] = false;
+              }
+          }
+      }
+
+      // All array[i] set to true are primes
+      for (let i = 2; i < n; i++) {
+          if(array[i]) {
+              output.push(i);
+          }
+      }
+
+      return output;
+    }
+
+    let simple = prime(10001);
+    let eraAlg = eratosthenes(105000);
+
+    expect(simple[10000]).toBe(eraAlg[10000]);
   });
-  */
+
 });

koans/AboutArrays.js

@@ -3,16 +3,16 @@ describe("About Arrays", function() {
   //We shall contemplate truth by testing reality, via spec expectations.
   it("should create arrays", function() {
     var emptyArray = [];
-    expect(typeof(emptyArray)).toBe(FILL_ME_IN); //A mistake? - http://javascript.crockford.com/remedial.html
-    expect(emptyArray.length).toBe(FILL_ME_IN);
+    expect(typeof(emptyArray)).toBe('object'); //A mistake? - http://javascript.crockford.com/remedial.html
+    expect(emptyArray.length).toBe(0);
 
     var multiTypeArray = [0, 1, "two", function () { return 3; }, {value1: 4, value2: 5}, [6, 7]];
-    expect(multiTypeArray[0]).toBe(FILL_ME_IN);
-    expect(multiTypeArray[2]).toBe(FILL_ME_IN);
-    expect(multiTypeArray[3]()).toBe(FILL_ME_IN);
-    expect(multiTypeArray[4].value1).toBe(FILL_ME_IN);
-    expect(multiTypeArray[4]["value2"]).toBe(FILL_ME_IN);
-    expect(multiTypeArray[5][0]).toBe(FILL_ME_IN);
+    expect(multiTypeArray[0]).toBe(0);
+    expect(multiTypeArray[2]).toBe("two");
+    expect(multiTypeArray[3]()).toBe(3);
+    expect(multiTypeArray[4].value1).toBe(4);
+    expect(multiTypeArray[4]["value2"]).toBe(5);
+    expect(multiTypeArray[5][0]).toBe(6);
   });
 
   it("should understand array literals", function () {
@@ -23,36 +23,36 @@ describe("About Arrays", function() {
     expect(array).toEqual([1]);
 
     array[1] = 2;
-    expect(array).toEqual([1, FILL_ME_IN]);
+    expect(array).toEqual([1, 2]);
 
     array.push(3);
-    expect(array).toEqual(FILL_ME_IN);
+    expect(array).toEqual([1, 2, 3]);
   });
 
   it("should understand array length", function () {
     var fourNumberArray = [1, 2, 3, 4];
 
-    expect(fourNumberArray.length).toBe(FILL_ME_IN);
+    expect(fourNumberArray.length).toBe(4);
     fourNumberArray.push(5, 6);
-    expect(fourNumberArray.length).toBe(FILL_ME_IN);
+    expect(fourNumberArray.length).toBe(6);
 
     var tenEmptyElementArray = new Array(10);
-    expect(tenEmptyElementArray.length).toBe(FILL_ME_IN);
+    expect(tenEmptyElementArray.length).toBe(10);
 
     tenEmptyElementArray.length = 5;
-    expect(tenEmptyElementArray.length).toBe(FILL_ME_IN);
+    expect(tenEmptyElementArray.length).toBe(5);
   });
 
   it("should slice arrays", function () {
     var array = ["peanut", "butter", "and", "jelly"];
 
-    expect(array.slice(0, 1)).toEqual(FILL_ME_IN);
-    expect(array.slice(0, 2)).toEqual(FILL_ME_IN);
-    expect(array.slice(2, 2)).toEqual(FILL_ME_IN);
-    expect(array.slice(2, 20)).toEqual(FILL_ME_IN);
-    expect(array.slice(3, 0)).toEqual(FILL_ME_IN);
-    expect(array.slice(3, 100)).toEqual(FILL_ME_IN);
-    expect(array.slice(5, 1)).toEqual(FILL_ME_IN);
+    expect(array.slice(0, 1)).toEqual(["peanut"]);
+    expect(array.slice(0, 2)).toEqual(["peanut", "butter"]);
+    expect(array.slice(2, 2)).toEqual([]);
+    expect(array.slice(2, 20)).toEqual(["and", "jelly"]);
+    expect(array.slice(3, 0)).toEqual([]);
+    expect(array.slice(3, 100)).toEqual(["jelly"]);
+    expect(array.slice(5, 1)).toEqual([]);
   });
 
   it("should know array references", function () {
@@ -62,36 +62,36 @@ describe("About Arrays", function() {
         refArray[1] = "changed in function";
     }
     passedByReference(array);
-    expect(array[1]).toBe(FILL_ME_IN);
+    expect(array[1]).toBe("changed in function");
 
     var assignedArray = array;
     assignedArray[5] = "changed in assignedArray";
-    expect(array[5]).toBe(FILL_ME_IN);
+    expect(array[5]).toBe("changed in assignedArray");
 
     var copyOfArray = array.slice();
     copyOfArray[3] = "changed in copyOfArray";
-    expect(array[3]).toBe(FILL_ME_IN);
+    expect(array[3]).toBe("three");
   });
 
   it("should push and pop", function () {
     var array = [1, 2];
     array.push(3);
 
-    expect(array).toEqual(FILL_ME_IN);
+    expect(array).toEqual([1, 2, 3]);
 
     var poppedValue = array.pop();
-    expect(poppedValue).toBe(FILL_ME_IN);
-    expect(array).toEqual(FILL_ME_IN);
+    expect(poppedValue).toBe(3);
+    expect(array).toEqual([1, 2]);
   });
 
   it("should know about shifting arrays", function () {
     var array = [1, 2];
 
     array.unshift(3);
-    expect(array).toEqual(FILL_ME_IN);
+    expect(array).toEqual([3, 1, 2]);
 
     var shiftedValue = array.shift();
-    expect(shiftedValue).toEqual(FILL_ME_IN);
-    expect(array).toEqual(FILL_ME_IN);
+    expect(shiftedValue).toEqual(3);
+    expect(array).toEqual([1, 2]);
   });
 });

koans/AboutExpects.js

@@ -4,20 +4,20 @@ describe('About Expects', function() {
   it('should expect true', function() {
 
     // Your journey begins here: Replace the word false with true 
-    expect(false).toBeTruthy();
+    expect(true).toBeTruthy();
   });
 
   // To understand reality, we must compare our expectations against reality.
   it('should expect equality', function() {
-    var expectedValue = FILL_ME_IN;
+    var expectedValue = 2;
     var actualValue = 1 + 1;
 
     expect(actualValue === expectedValue).toBeTruthy();
   });
 
   // Some ways of asserting equality are better than others.
   it('should assert equality a better way', function() {
-    var expectedValue = FILL_ME_IN;
+    var expectedValue = 2;
     var actualValue = 1 + 1;
 
   // toEqual() compares using common sense equality.
@@ -26,7 +26,7 @@ describe('About Expects', function() {
 
   // Sometimes you need to be precise about what you "type."
   it('should assert equality with ===', function() {
-    var expectedValue = FILL_ME_IN;
+    var expectedValue = "2";
     var actualValue = (1 + 1).toString();
 
   // toBe() will always use === to compare.
@@ -35,6 +35,6 @@ describe('About Expects', function() {
 
   // Sometimes we will ask you to fill in the values.
   it('should have filled in values', function() {
-    expect(1 + 1).toEqual(FILL_ME_IN);
+    expect(1 + 1).toEqual(2);
   });
 });