elementary algorithm JavaScript solutions added

elementaryAlgo/alternateCap.js

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+// Write a function `alternatingCaps` that accepts a sentence string as an argument. The function should
+// return the sentence where words alternate between lowercase and uppercase.
+const alternatingCaps = (words) => {
+  let result = "";
+  let arraySplit = words.split(" ");
+  for (let i = 0; i < arraySplit.length; i++) {
+    let word = arraySplit[i];
+    if (i % 2 === 0) {
+      result += word.toLowerCase() + " ";
+    } else {
+      result += word.toUpperCase() + " ";
+    }
+  }
+  return result;
+};
+console.log(alternatingCaps("take them to school")); // 'take THEM to SCHOOL'
+console.log(alternatingCaps("What did ThEy EAT before?")); // 'what DID they EAT before?'

elementaryAlgo/bleepVowels.js

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+// Write a function `bleepVowels` that accepts a string as an argument. The function should return
+// a new string where all vowels are replaced with `*`s. Vowels are the letters a, e, i, o, u.
+function bleepVowels(str) {
+  let array = ["a", "e", "i", "o", "u"];
+  let result = "";
+  for (let i = 0; i < str.length; i++) {
+    let char = str[i];
+    if (array.indexOf(char) > -1) {
+      result += "*";
+    } else {
+      result += char;
+    }
+  }
+  return result;
+}
+console.log(bleepVowels("skateboard")); // 'sk*t*b**rd'
+console.log(bleepVowels("slipper")); // 'sl*pp*r'
+console.log(bleepVowels("range")); // 'r*ng*'
+console.log(bleepVowels("brisk morning")); // 'br*sk m*rn*ng'

elementaryAlgo/chooseDivisible.js

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+// Write a function `chooseDivisibles(numbers, target)` that accepts an array of numbers and a
+// target number as arguments. The function should return an array containing elements of the original
+// array that are divisible by the target.
+const chooseDivisibles = (numbers, target) => {
+  let result = [];
+  for (let i = 0; i < numbers.length; i++) {
+    let num = numbers[i];
+    if (num % target === 0) {
+      result.push(num);
+    }
+  }
+  return result;
+};
+console.log(chooseDivisibles([40, 7, 22, 20, 24], 4)); // [40, 20, 24]
+console.log(chooseDivisibles([9, 33, 8, 17], 3)); // [9, 33]
+console.log(chooseDivisibles([4, 25, 1000], 10)); // [1000]

elementaryAlgo/commonElement.js

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+// Write a function `commonElements` that accepts two arrays as arguments. The function should return
+// a new array containing the elements that are found in both of the input arrays. The order of
+// the elements in the output array doesn't matter as long as the function returns the correct elements.
+const commonElements = (array1, array2) => {
+  let result = [];
+  let set1 = new Set(array1);
+  let set2 = new Set(array2);
+  for (let elem of set1) {
+    if (set2.has(elem)) {
+      result.push(elem);
+    }
+  }
+  return result;
+};
+let arr1 = ["a", "c", "d", "b"];
+let arr2 = ["b", "a", "y"];
+console.log(commonElements(arr1, arr2)); // ['a', 'b']
+
+let arr3 = [4, 7];
+let arr4 = [32, 7, 1, 4];
+console.log(commonElements(arr3, arr4)); // [4, 7]

elementaryAlgo/divisors.js

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+// Write a function `divisors` that accepts a number as an argument. The function should return an
+// array containing all positive numbers that can divide into the argument.
+function divisors(num) {
+  let result = [];
+  for (let i = 1; i <= num; i++) {
+    let eachNum = i;
+    if (num % eachNum === 0) {
+      result.push(eachNum);
+    }
+  }
+  return result;
+}
+console.log(divisors(15)); // [1, 3, 5, 15]
+console.log(divisors(7)); // [1, 7]
+console.log(divisors(24)); // [1, 2, 3, 4, 6, 8, 12, 24]

elementaryAlgo/filterLongWords.js

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+// Write a function `filterLongWords` that accepts an array of strings as an argument. The function
+// should return a new array containing only the strings that are less than 5 characters long.
+function filterLongWords(array) {
+  let result = [];
+  for (let i = 0; i < array.length; i++) {
+    let word = array[i];
+    if (word.length < 5) {
+      result.push(word);
+    }
+  }
+  return result;
+}
+console.log(filterLongWords(["kale", "cat", "retro", "axe", "heirloom"]));
+// ['kale', 'cat', 'axe']
+
+console.log(filterLongWords(["disrupt", "pour", "trade", "pic"]));
+// ['pour', 'pic']

elementaryAlgo/lengthiestWord.js

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+// Write a function `lengthiestWord` that accepts a sentence string as an argument. The function should
+// return the longest word of the sentence. If there is a tie, return the word that appears later
+// in the sentence.
+const lengthiestWord = (words) => {
+  let arrayWord = words.split(" ");
+  let lengthiest = arrayWord[0];
+  for (let i = 1; i < arrayWord.length; i++) {
+    let word = arrayWord[i];
+    if (lengthiest.length <= word.length) {
+      lengthiest = word;
+    }
+  }
+  return lengthiest;
+};
+console.log(lengthiestWord("I am pretty hungry")); // 'hungry'
+console.log(lengthiestWord("we should think outside of the box")); // 'outside'
+console.log(lengthiestWord("down the rabbit hole")); // 'rabbit'
+console.log(lengthiestWord("simmer down")); // 'simmer'

elementaryAlgo/makeAcronyms.js

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+// Write a function `makeAcronym` that accepts a sentence string as an argument. The function should
+// return a string containing the first character of each word in the sentence.
+const makeAcronym = (words) => {
+  let arrayWord = words.split(" ");
+  let result = "";
+  for (let i = 0; i < arrayWord.length; i++) {
+    let word = arrayWord[i][0];
+    result += word.toUpperCase();
+  }
+  return result;
+};
+console.log(makeAcronym("New York")); // NY
+console.log(makeAcronym("same stuff different day")); // SSDD
+console.log(makeAcronym("Laugh out loud")); // LOL
+console.log(makeAcronym("don't over think stuff")); // DOTS

elementaryAlgo/makeMatrix.js

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+// Write a function `makeMatrix(m, n, value)` that accepts three arguments. The function should return
+// a 2-dimensional array of height `m` and width `n` that contains the `value` as every element.
+const makeMatrix = (m, n, value) => {
+  let matrix = [];
+  for (let i = 0; i < m; i++) {
+    let row = [];
+    for (let j = 0; j < n; j++) {
+      row.push(value);
+    }
+    matrix.push(row);
+  }
+  return matrix;
+};
+// const makeMatrix = (m, n, value) => {
+//   let matrix = Array.from(Array(m), () => Array(n).fill(value));
+//   return matrix
+// };
+console.log(makeMatrix(3, 5, null));
+// [
+//   [ null, null, null, null, null ],
+//   [ null, null, null, null, null ],
+//   [ null, null, null, null, null ]
+// ]
+
+console.log(makeMatrix(4, 2, "x"));
+// [
+//   [ 'x', 'x' ],
+//   [ 'x', 'x' ],
+//   [ 'x', 'x' ],
+//   [ 'x', 'x' ]
+// ]
+
+console.log(makeMatrix(2, 2, 0));
+// [
+//   [ 0, 0 ],
+//   [ 0, 0 ]
+// ]

elementaryAlgo/maximum.js

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+// Write a function `maximum` that accepts an array of numbers as an argument. The function should
+// return the largest number of the array. If the array is empty, then the function should return null.
+const maximum = (array) => {
+  if (array.length === 0) return null;
+  let max = array[0];
+  for (let i = 1; i < array.length; i++) {
+    let elem = array[i];
+    max = Math.max(max, elem);
+  }
+  return max;
+};
+console.log(maximum([5, 6, 3, 7])); // 7
+console.log(maximum([17, 15, 19, 11, 2])); // 19
+console.log(maximum([])); // null

elementaryAlgo/numOdd.js

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+// Write a function `numOdds` that accepts an array of numbers as an argument. The function should
+// return a number representing the count of odd elements in the array.
+function numOdds(array) {
+  let count = 0;
+  for (let i = 0; i < array.length; i++) {
+    let num = array[i];
+    if (num % 2 === 1) count++;
+  }
+  return count;
+}
+console.log(numOdds([4, 7, 2, 5, 9])); // 3
+console.log(numOdds([11, 31, 58, 99, 21, 60])); // 4
+console.log(numOdds([100, 40, 4])); // 0

elementaryAlgo/numberRange.js

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+// Write a function `numberRange(min, max, step)` that accepts three numbers as arguments, `min`,
+// `max`, and `step`. The function should return all numbers between `min` and `max` at `step` intervals.
+// `min` and `max` are inclusive.
+const numberRange = (min, max, step) => {
+  let result = [];
+  for (let i = min; i <= max; i += step) {
+    result.push(i);
+  }
+  return result;
+};
+console.log(numberRange(10, 40, 5)); // [10, 15, 20, 25, 30, 35, 40]
+console.log(numberRange(14, 24, 3)); // [14, 17, 20, 23]
+console.log(numberRange(8, 35, 6)); // [8, 14, 20, 26, 32]

elementaryAlgo/pairPrint.js

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+// Write a function `pairPrint` that accepts an array as an argument. The function should print
+// all unique pairs of elements in the array. The function doesn't need to return any value. It
+// should just print to the terminal.
+function pairPrint(arr) {
+  for (let i = 0; i < arr.length; i++) {
+    for (let j = i + 1; j < arr.length; j++) {
+      console.log(arr[i], arr[j]);
+    }
+  }
+}
+
+
+pairPrint(["artichoke", "broccoli", "carrot", "daikon"]);
+// prints
+//  artichoke - broccoli
+//  artichoke - carrot
+//  artichoke - daikon
+//  broccoli - carrot
+//  broccoli - daikon
+//  carrot - daikon
+
+//pairPrint(["apple", "banana", "clementine"]);
+// prints
+//  apple - banana
+//  apple - clementine
+//  banana - clementine

elementaryAlgo/print2d.js

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+// Write a function `print2d` that accepts a two-dimensional array as an argument. The function
+// should print all inner elements of the array.
+const print2d = (array) => {
+  for (let i = 0; i < array.length; i++) {
+    let innerElem = array[i];
+    for (let j = 0; j < innerElem.length; j++) {
+      console.log(innerElem[j]);
+    }
+  }
+};
+let array1 = [
+  ["a", "b", "c", "d"],
+  ["e", "f"],
+  ["g", "h", "i"],
+];
+print2d(array1);
+// prints
+//  a
+//  b
+//  c
+//  d
+//  e
+//  f
+//  g
+//  h
+//  i
+
+let array2 = [[9, 3, 4], [11], [42, 100]];
+print2d(array2);
+// prints
+//  9
+//  3
+//  4
+//  11
+//  42
+//  100

elementaryAlgo/printCombination.js

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+// Write a function `printCombinations`that accepts two arrays as arguments. The function should
+// print all combinations of the elements generated by taking an element from the first array and
+// and an element from the second array. The function doesn't need to return any value. It
+// should just print to the terminal.
+function printCombinations(array1, array2) {
+  for (let i = 0; i < array1.length; i++) {
+    const element1 = array1[i];
+    for (let j = 0; j < array2.length; j++) {
+      let element2 = array2[j];
+      console.log(element1, element2);
+    }
+  }
+}
+
+let colors = ["gray", "cream", "cyan"];
+let clothes = ["shirt", "flannel"];
+
+printCombinations(colors, clothes);
+// prints
+//  gray shirt
+//  gray flannel
+//  cream shirt
+//  cream flannel
+//  cyan shirt
+//  cyan flannel
+
+//printCombinations(["hot", "cold"], ["soup", "tea"]);
+// prints
+//  hot soup
+//  hot tea
+//  cold soup
+//  cold tea

elementaryAlgo/recursionArray.js

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+//Given an array of integers, write a function that return the sum all of it element using recursion
+const sum = (array) => {
+  if (array.length === 0) return 0;
+  let rest = array.slice(1);
+  return array[0] + sum(rest);
+};
+console.log(sum([2, 5, 6, 8, 9]));
+//Time: O(n^2)
+//Space: O(n)
+// can improve our space complexity like this
+const sumImprove = (array) => {
+  return _sum(array, 0);
+};
+const _sum = (array, idx) => {
+  if (array.length === idx) return 0;
+  return array[idx] + _sum(array, idx + 1);
+};
+console.log(sumImprove([2, 5, 6, 8, 9]));
+//Time: O(n)
+//Space: O(n)

elementaryAlgo/removeFirstVowel.js

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+// Write a function `removeFirstVowel` that accepts a string as an argument. The function should return
+// the string with it's first vowel removed.
+const removeFirstVowel = (words) => {
+  let vowels = ["a", "e", "i", "o", "u"];
+  for (let i = 0; i < words.length; i++) {
+    let word = words[i];
+    if (vowels.includes(word)) {
+      let copy = words.split("");
+      copy.splice(i, 1);
+      return copy.join("");
+    }
+  }
+  return words;
+};
+console.log(removeFirstVowel("volcano")); // 'vlcano'
+console.log(removeFirstVowel("celery")); // 'clery'
+console.log(removeFirstVowel("juice")); // 'jice'
+console.log(removeFirstVowel("ghshsh"));

elementaryAlgo/removeShortWords.js

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+// Write a function `removeShortWords` that accepts a sentence string as an argument. The function
+// should return a new sentence where all of the words shorter than 4 characters are removed.
+const removeShortWords = (words) => {
+  let result = "";
+  let arrayWords = words.split(" ");
+  for (let i = 0; i < arrayWords.length; i++) {
+    let word = arrayWords[i];
+    if (word.length < 4) continue;
+    else result += word + " ";
+  }
+  return result;
+};
+console.log(removeShortWords("knock on the door will you")); // 'knock door will'
+console.log(removeShortWords("a terrible plan")); // 'terrible plan'
+console.log(removeShortWords("run faster that way")); // 'faster that'

elementaryAlgo/reverseArray.js

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+// Write a function `reverseArray` that accepts an array as an argument. The function should return a
+// array containing the elements of the original array in reverse order.
+const reverseArray = (array) => {
+  let result = [];
+  for (let i = array.length - 1; i >= 0; i--) {
+    let element = array[i];
+    result.push(element);
+  }
+  return result;
+};
+console.log(reverseArray(["zero", "one", "two", "three"])); // ['three', 'two', 'one', 'zero']
+console.log(reverseArray([7, 1, 8])); // [8, 1, 7]