diff --git a/SpecRunner.html b/SpecRunner.html
index 5a18ca964..412a86e39 100644
--- a/SpecRunner.html
+++ b/SpecRunner.html
@@ -29,7 +29,7 @@
});
-
+
diff --git a/spec/part1.js b/spec/part1.js
index f2ec9ba33..72360c485 100755
--- a/spec/part1.js
+++ b/spec/part1.js
@@ -84,7 +84,7 @@
- xdescribe('3. Sum Integers in Array', function() {
+ describe('3. Sum Integers in Array', function() {
it('should return a number', function() {
expect(typeof(arraySum([[1],[2,3],[[4]],5,6]))).to.eql('number');
@@ -402,7 +402,7 @@
- xdescribe('11. Modulo', function() {
+ describe('11. Modulo', function() {
it('should return a number', function() {
expect(typeof(modulo(5,2))).to.equal('number');
@@ -476,7 +476,7 @@
- xdescribe('13. Divide', function() {
+ describe('13. Divide', function() {
it('should return a number', function() {
expect(typeof(divide(5,2))).to.equal('number');
@@ -512,7 +512,7 @@
- xdescribe('14. Greatest Common Divisor', function() {
+ describe('14. Greatest Common Divisor', function() {
it('should return a number', function() {
expect(typeof(gcd(4,36))).to.equal('number');
@@ -726,7 +726,7 @@
- xdescribe('21. Count key in object', function() {
+ describe('21. Count key in object', function() {
var input = {'e': {'x':'y'}, 't':{'r': {'e':'r'}, 'p': {'y':'r'}},'y':'e'};
it('should return a number', function() {
@@ -756,7 +756,7 @@
- xdescribe('22. Count value in object', function() {
+ describe('22. Count value in object', function() {
var input = {'e': {'x':'y'}, 't':{'r': {'e':'r'}, 'p': {'y':'r'}},'y':'e'};
it('should return a number', function() {
@@ -786,7 +786,7 @@
- xdescribe('23. Replace keys in object', function() {
+ describe('23. Replace keys in object', function() {
var tallyKeys = function(obj) {
var count = 0;
@@ -850,7 +850,7 @@
});
- xdescribe('24. First n Fibonacci', function() {
+ describe('24. First n Fibonacci', function() {
it('should return an array', function() {
expect(Array.isArray(fibonacci(5))).to.equal(true);
@@ -961,7 +961,7 @@
- xdescribe('28. Sum even numbers in nested objects', function() {
+ describe('28. Sum even numbers in nested objects', function() {
var obj = {
a: 2,
b: {b: 2, bb: {b: 3, bb: {b: 2}}},
@@ -990,7 +990,7 @@
- xdescribe('29. Flatten nested arrays', function() {
+ describe('29. Flatten nested arrays', function() {
it('should return an array', function() {
expect(Array.isArray(flatten([1,[2],[3,[[4]]],5]))).to.equal(true);
@@ -1073,7 +1073,7 @@
- xdescribe('32. Augment each element in nested arrays', function() {
+ describe('32. Augment each element in nested arrays', function() {
it('should return an array', function() {
expect(Array.isArray(augmentElements([[],[3],[7]], 5))).to.equal(true);
@@ -1147,7 +1147,7 @@
- xdescribe('35. Convert numbers to text', function() {
+ describe('35. Convert numbers to text', function() {
it('should return a string', function() {
expect(typeof(numToText("I have 5 dogs and 6 ponies"))).to.equal('string');
diff --git a/src/recursion.js b/src/recursion.js
index e92a8866c..4e3928ff5 100644
--- a/src/recursion.js
+++ b/src/recursion.js
@@ -5,31 +5,84 @@
// Example: 5! = 5 x 4 x 3 x 2 x 1 = 120
// factorial(5); // 120
var factorial = function(n) {
+ if (n < 0 ) { return null }
+ if (n < 1) { return 1 }
+ else { return n * factorial(n - 1) }
};
// 2. Compute the sum of an array of integers.
// Example: sum([1, 2, 3, 4, 5, 6]); // 21
var sum = function(array) {
+ if (!array.length) { return 0 }
+ return array[0] + sum(array.slice(1));
+
};
// 3. Sum all numbers in an array containing nested arrays.
// Example: arraySum([1,[2,3],[[4]],5]); // 15
-var arraySum = function(array) {
+var arraySum = function(array, sum = 0) { // if array.length = 1, return array[0]
+ var sum = 0;
+
+ for (var i = 0; i < array.length; i++) {
+ if (array[i] === Math.round(array[i])) {
+ sum += array[i];
+ }
+ if (array[i] instanceof Array) {
+ sum += arraySum(array[i]); //This will apply the same function to the current Array element which is an Array
+ }
+ }
+ return sum;
};
// 4. Check if a number is even.
var isEven = function(n) {
+ if (n === 0) {
+ return true;
+ } else if (n === 1) {
+ return false;
+ } else if (n < 0) {
+ return isEven(-n);
+ } else {
+ return isEven(n - 2);
+ }
};
// 5. Sum all integers below a given integer.
// sumBelow(10); // 45
// sumBelow(7); // 21
+
var sumBelow = function(n) {
-};
+ var x = n - 2;
+ var y = n - 1;
+ var z = n + 1;
+
+ if (n == 0) { return n } // returns 0 when given n is 0
+
+ else if (n < 0 ) { return z + sumBelow(n + 1) }
+
+ else if (x < 1) { return y } // handles n = 1 case and returns 0
+
+ else if (n > 1 && x > -1) { return y + sumBelow(n - 1) } // sums n - 1 with recursion of n - 1
+ };
// 6. Get the integers in range (x, y).
// Example: range(2, 9); // [3, 4, 5, 6, 7, 8]
-var range = function(x, y) {
+var range = function(x, y) { // return an array of nums bt x & y (exclusive of x & y)
+ if (x === y || (x - y) === 1 || y -x === 1) { //base case, if there are no numbers bt x & y
+ return [];
+ } else if (x < y && y - x === 2) {
+ return [x + 1];
+ } else if (x > y && x - y === 2) {
+ return [y + 1]
+ } else if (x > y) {
+ var rangeArr = range(x - 1, y);
+ rangeArr.unshift(x - 1);
+ return rangeArr;
+ } else if (x < y) {
+ var rangeArr = range(x, y - 1);
+ rangeArr.push(y - 1);
+ return rangeArr;
+ }
};
// 7. Compute the exponent of a number.
@@ -38,6 +91,13 @@ var range = function(x, y) {
// Example: exponent(4,3); // 64
// https://www.khanacademy.org/computing/computer-science/algorithms/recursive-algorithms/a/computing-powers-of-a-number
var exponent = function(base, exp) {
+ if (exp === 0) { // base test is when exponent = 0
+ return 1 // return 1
+ } else if (exp > 0) {
+ return base * exponent(base, exp - 1)
+ } else if (exp < 0) {
+ return 1 / exponent(base, -exp);
+ }
};
// 8. Determine if a number is a power of two.
@@ -45,14 +105,31 @@ var exponent = function(base, exp) {
// powerOfTwo(16); // true
// powerOfTwo(10); // false
var powerOfTwo = function(n) {
+ if (n === 2 || n === 1) { return true } // base case true
+ if (n === 0 || n === 3) { return false } // base case false
+ if (n < 0) { return powerOfTwo(-n) } // case neg recurses w abs val
+ if (n < 2) {return false} // case if n b/t 0 & 2 = false
+ else {return powerOfTwo(n / 2)} // else recurses to divide n by 2
+
};
// 9. Write a function that accepts a string a reverses it.
-var reverse = function(string) {
+var reverse = function(string, revStr = "", ind = string.length -1 ) {
+ if (ind < 0) { return revStr } // base case
+ revStr += string[ind] ; // adds last letter of string to revStr
+ return reverse(string, revStr,--ind); // returns recursive call
};
// 10. Write a function that determines if a string is a palindrome.
var palindrome = function(string) {
+ string = string.toLowerCase().replace(' ', '');
+ if(string.length < 2) {
+ return true;
+ } else if (string[0] !== string [string.length -1]){
+ return false;
+ }
+ return palindrome(string.substr(1, string.length -2));
+ // a palindrome is a word that is the same word spelled backwards as forward
};
// 11. Write a function that returns the remainder of x divided by y without using the
@@ -61,16 +138,36 @@ var palindrome = function(string) {
// modulo(17,5) // 2
// modulo(22,6) // 4
var modulo = function(x, y) {
+ if (y === 0 ) { return NaN };
+ if (x < 0) { return -modulo(-x, y) }
+ if (y < 0) { return modulo(x, -y) }
+ if (x < y) { return x}
+ return modulo(x-y, y)
};
// 12. Write a function that multiplies two numbers without using the * operator or
// JavaScript's Math object.
var multiply = function(x, y) {
+ var product = x;
+ if (y == 0) return 0;
+ else if (y >= 1) {
+ return product + multiply(product, --y);
+ }
+ else if (y <= -1) {
+ return -product + multiply(product, ++y);
+ }
};
// 13. Write a function that divides two numbers without using the / operator or
// JavaScript's Math object.
var divide = function(x, y) {
+ var posx = x - x < x ? x : (x - x) - x;
+ if (y === 0) { return NaN }
+ else if (y === 1) { return x }
+ else if (x === 0 || (posx < y)) { return 0 }
+ else if (x < 0 && y < 0) { return divide(-x, -y) }
+ else if (x > 0 && y > 0) { return divide(x - y, y) + 1 }
+ else if ((x < 0 && y > 0) || (x > 0 && y < 0)) { return divide(x + y, y) - 1 }
};
// 14. Find the greatest common divisor (gcd) of two positive numbers. The GCD of two
@@ -79,6 +176,10 @@ var divide = function(x, y) {
// http://www.cse.wustl.edu/~kjg/cse131/Notes/Recursion/recursion.html
// https://www.khanacademy.org/computing/computer-science/cryptography/modarithmetic/a/the-euclidean-algorithm
var gcd = function(x, y) {
+ if (x === y) { return x }
+ else if (x < 0 || y < 0) { return null }
+ else if (x > y) { return gcd(x - y, y) }
+ else { return gcd(x, y - x) }
};
// 15. Write a function that compares each character of two strings and returns true if
@@ -87,39 +188,77 @@ var gcd = function(x, y) {
// compareStr('', '') // true
// compareStr('tomato', 'tomato') // true
var compareStr = function(str1, str2) {
+ if (str1.length <= 1 || str2.length <= 1) {
+ if (str1.length !== str2.length) { return false }
+ else { return (str1[0] === str2[0]) }
+ } else { return compareStr(str1.slice(1), str2.slice(1)) }
};
// 16. Write a function that accepts a string and creates an array where each letter
// occupies an index of the array.
var createArray = function(str){
+ if (str.length === 0) { return [] }
+ else {
+ return createArray(str.slice(0, str.length-1)).concat(str[str.length-1])
+ }
};
// 17. Reverse the order of an array
var reverseArr = function (array) {
+ if (array.length <= 1) { return array }
+ else if (array.length === 2) {
+ return [array[1], array[0]]
+ } else {
+ return reverseArr(array.slice(1)).concat([array[0]])
+ }
};
// 18. Create a new array with a given value and length.
// buildList(0,5) // [0,0,0,0,0]
// buildList(7,3) // [7,7,7]
var buildList = function(value, length) {
+ if (length === 0) { return [] }
+ else { return buildList(value, length-1).concat([value]) }
};
// 19. Count the occurence of a value inside a list.
// countOccurrence([2,7,4,4,1,4], 4) // 3
// countOccurrence([2,'banana',4,4,1,'banana'], 'banana') // 2
-var countOccurrence = function(array, value) {
+var countOccurrence = function(array, value, count=0) {
+ if (array.length === 0 ) {
+ return count;
+ } if (array[0] === value) {
+ count += 1;
+ }
+ return countOccurrence(array.slice(1), value, count);
};
// 20. Write a recursive version of map.
// rMap([1,2,3], timesTwo); // [2,4,6]
-var rMap = function(array, callback) {
+var rMap = function(array, callback, newArr = []) {
+ if (array.length === 0) {
+ return newArr;
+ }
+ newArr.push(callback(array[0]))
+
+ return rMap(array.slice(1), callback, newArr);
};
// 21. Write a function that counts the number of times a key occurs in an object.
// var testobj = {'e': {'x':'y'}, 't':{'r': {'e':'r'}, 'p': {'y':'r'}},'y':'e'};
// countKeysInObj(testobj, 'r') // 1
// countKeysInObj(testobj, 'e') // 2
-var countKeysInObj = function(obj, key) {
+var countKeysInObj = function(obj, key, keyCount = 0) { // use Object.keys
+ var allKeys = Object.keys(obj); // get them keys!!!
+ if (allKeys.length === 1) { //
+ return +(allKeys[0] === key); //
+ } else {
+ for (var k in obj) { // iterate over obj to count keys matching given
+ keyCount += +(k === key) + countKeysInObj(obj[k], key)
+ }
+ return keyCount;
+ }
+
};
// 22. Write a function that counts the number of times a value occurs in an object.
@@ -127,11 +266,37 @@ var countKeysInObj = function(obj, key) {
// countValuesInObj(testobj, 'r') // 2
// countValuesInObj(testobj, 'e') // 1
var countValuesInObj = function(obj, value) {
+ var allKeys = Object.keys(obj); // grabs all keys (including nested objs)
+ if (allKeys.length === 1 && typeof obj[allKeys[0]] !== 'object') {
+ return +(obj[allKeys[0]] === value)
+ } else {
+ var subTotal = 0;
+ for (var k in obj) {
+ subTotal += countValuesInObj(obj[k], value)
+ }
+ return subTotal;
+ }
};
// 23. Find all keys in an object (and nested objects) by a provided name and rename
// them to a provided new name while preserving the value stored at that key.
var replaceKeysInObj = function(obj, key, newKey) {
+ var themKeys = Object.keys(obj);
+ if (themKeys.length === 1 && typeof obj[themKeys[0]] !== 'object') {
+ if (themKeys[0] === key) {
+ obj[newKey] = obj[key];
+ delete obj[key];
+ }
+ } else {
+ for (var k in obj) {
+ replaceKeysInObj(obj[k], key, newKey);
+ if (k === key) {
+ obj[newKey] = obj[key];
+ delete obj[key];
+ }
+ }
+ }
+ return obj
};
// 24. Get the first n Fibonacci numbers. In the Fibonacci Sequence, each subsequent
@@ -140,6 +305,11 @@ var replaceKeysInObj = function(obj, key, newKey) {
// fibonacci(5); // [0, 1, 1, 2, 3, 5]
// Note: The 0 is not counted.
var fibonacci = function(n) {
+ if (n < 1) { return null; }
+ if (n === 1) { return [0, 1]; }
+ var prevFib = fibonacci(n-1);
+ var prevLen = prevFib.length;
+ return prevFib.concat(prevFib[prevLen - 1] + prevFib[prevLen - 2]);
};
// 25. Return the Fibonacci number located at index n of the Fibonacci sequence.
@@ -148,17 +318,26 @@ var fibonacci = function(n) {
// nthFibo(7); // 13
// nthFibo(3); // 2
var nthFibo = function(n) {
+ if (n < 0) { return null } // we got base!
+ if (n === 0) { return 0 }
+ if (n === 1) { return 1 }
+ return nthFibo(n - 1) + nthFibo(n - 2) // recurse, adding 2 nums prev to n
};
// 26. Given an array of words, return a new array containing each word capitalized.
// var words = ['i', 'am', 'learning', 'recursion'];
// capitalizedWords(words); // ['I', 'AM', 'LEARNING', 'RECURSION']
var capitalizeWords = function(input) {
+ if (input.length === 0) { return input }
+ return [input[0].toUpperCase()].concat(capitalizeWords(input.slice(1)));
};
// 27. Given an array of strings, capitalize the first letter of each index.
// capitalizeFirst(['car', 'poop', 'banana']); // ['Car', 'Poop', 'Banana']
var capitalizeFirst = function(array) {
+ if (array.length === 0) { return array } // base case, empty array
+ var newWord = array[0][0].toUpperCase() + array[0].slice(1); // cap the init ltr
+ return [newWord].concat(capitalizeFirst(array.slice(1))); // recurse, adding new Word to array
};
// 28. Return the sum of all even numbers in an object containing nested objects.
@@ -171,16 +350,35 @@ var capitalizeFirst = function(array) {
// };
// nestedEvenSum(obj1); // 10
var nestedEvenSum = function(obj) {
+ var total = 0;
+ for (key in obj) {
+ if (typeof obj[key] === 'number' && obj[key] % 2 === 0) {
+ total += obj[key];
+ } else if (typeof obj[key] === 'object') {
+ total += nestedEvenSum(obj[key]);
+ }
+ }
+ return total;
};
// 29. Flatten an array containing nested arrays.
// Example: flatten([1,[2],[3,[[4]]],5]); // [1,2,3,4,5]
var flatten = function(arrays) {
+ if (arrays.length === 0) { return arrays; }
+ if (!Array.isArray(arrays[0])) {
+ return [arrays[0]].concat(flatten(arrays.slice(1)));
+ } else {
+ return flatten(arrays[0]).concat(flatten(arrays.slice(1)));
+ }
};
// 30. Given a string, return an object containing tallies of each letter.
// letterTally('potato'); // {'p':1, 'o':2, 't':2, 'a':1}
var letterTally = function(str, obj) {
+ var obj = obj || {};
+ if (str === '') { return obj }
+ obj[str[0]] = obj[str[0]] + 1 || 1;
+ return letterTally(str.slice(1), obj);
};
// 31. Eliminate consecutive duplicates in a list. If the list contains repeated
@@ -189,18 +387,27 @@ var letterTally = function(str, obj) {
// Example: compress([1, 2, 2, 3, 4, 4, 5, 5, 5]) // [1, 2, 3, 4, 5]
// Example: compress([1, 2, 2, 3, 4, 4, 2, 5, 5, 5, 4, 4]) // [1, 2, 3, 4, 2, 5, 4]
var compress = function(list) {
+ if (list.length < 2) { return list }
+ if (list[0] === list[1]) { return compress(list.slice(1)) }
+ return [list[0]].concat(compress(list.slice(1)))
};
// 32. Augument every element in a list with a new value where each element is an array
// itself.
// Example: augmentElements([[],[3],[7]], 5); // [[5],[3,5],[7,5]]
var augmentElements = function(array, aug) {
+ var aug0 = array[0].concat(aug);
+ if (array.length === 1) { return [aug0]; }
+ return [aug0].concat(augmentElements(array.slice(1), aug));
};
// 33. Reduce a series of zeroes to a single 0.
// minimizeZeroes([2,0,0,0,1,4]) // [2,0,1,4]
// minimizeZeroes([2,0,0,0,1,0,0,4]) // [2,0,1,0,4]
var minimizeZeroes = function(array) {
+ if (array.length < 2) { return array }
+ if (array[0] + array[1] === 0) { return minimizeZeroes(array.slice(1)) }
+ return [array[0]].concat(minimizeZeroes(array.slice(1)))
};
// 34. Alternate the numbers in an array between positive and negative regardless of
@@ -208,29 +415,77 @@ var minimizeZeroes = function(array) {
// alternateSign([2,7,8,3,1,4]) // [2,-7,8,-3,1,-4]
// alternateSign([-2,-7,8,3,-1,4]) // [2,-7,8,-3,1,-4]
var alternateSign = function(array) {
+ if (array.length === 0) { return array }
+ if (array.length === 1) { return [Math.abs(array[0])] }
+ var new2 = [Math.abs(array[0]), -1 * Math.abs(array[1])]
+ return new2.concat(alternateSign(array.slice(2)))
};
// 35. Given a string, return a string with digits converted to their word equivalent.
// Assume all numbers are single digits (less than 10).
// numToText("I have 5 dogs and 6 ponies"); // "I have five dogs and six ponies"
var numToText = function(str) {
+ var trans = {
+ '1': 'one', '2': 'two', '3': 'three', '4': 'four',
+ '5': 'five', '6': 'six', '7': 'seven', '8': 'eight',
+ '9': 'nine', '0': 'zero'
+ }
+ if (str.length === 0) { return str }
+ if (trans[str[0]] !== undefined) {
+ return trans[str[0]].concat(numToText(str.slice(1)))
+ } else { return str[0].concat(numToText(str.slice(1))) }
};
// *** EXTRA CREDIT ***
// 36. Return the number of times a tag occurs in the DOM.
var tagCount = function(tag, node) {
+ var tagTotal = 0;
+ var node = node || document.body;
+ if (node.nodeType != Node.TEXT_NODE) {
+ if (node.tagName === tag.toUpperCase()) { tagTotal++; }
+ }
+ if (node.hasChildNodes()) {
+ node.childNodes.forEach(child => tagTotal += tagCount(tag, child));
+ }
+ return tagTotal;
};
// 37. Write a function for binary search.
// Sample array: [0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15]
// console.log(binarySearch(5)) will return '5'
+// FD: A Binary search will return index of nth element in array. So slice it like a phone book
var binarySearch = function(array, target, min, max) {
+ var max = array.length;
+ if (target < array[0] || target > array[max - 1]) { return null } // base if target not found
+ var mid = Math.floor(max / 2); // determines mid-point and rounds down
+ if (array[mid] === target) { return mid }
+ if (max <= 1) { return null }
+ if (array[mid] < target) {
+ var recurseResult = binarySearch(array.slice(mid), target);
+ return recurseResult === null ? null : mid + recurseResult;
+ } else {
+ return binarySearch(array.slice(0, mid), target);
+ }
};
// 38. Write a merge sort function.
// Sample array: [34,7,23,32,5,62]
// Sample output: [5,7,23,32,34,62]
var mergeSort = function(array) {
+ if (array.length < 2) { return array } // base: if 1 element remains, nothing to sort, so return the array
+ // review pseudo code tree structure
+ // mid, subArrLeft & subArr Right
+ var midInd = Math.floor(array.length / 2); // split the array: middle index
+ var subArrLeft = mergeSort(array.slice(0, midInd));
+ var subArrRight = mergeSort(array.slice(midInd));
+ return merge(subArrLeft, subArrRight);
+}
+
+ function merge (leftArr, rightArr) { // had to build merge func...couldn't figure out how otherwise
+ var result = [];
+ while (leftArr.length > 0 && rightArr.length > 0) // hate whiles but this works
+ result.push(leftArr[0] < rightArr[0]? leftArr.shift() : rightArr.shift()); //reorders and rebuilds from both sides (push & shift)
+ return result.concat(leftArr.length? leftArr : rightArr); //concats the Arr w/ a length
};