LAB solution - M1 | Functions and Arrays - WDFT EN 10/2020

functions-and-arrays.js

// Iteration #1: Find the maximum
const maxOfTwoNumbers = (a, b) => {
  if(a > b) return a;
  else if (b > a) return b;
  else return a
};


// Iteration #2: Find longest word
const words = ['mystery', 'brother', 'aviator', 'crocodile', 'pearl', 'orchard', 'crackpot'];

function findLongestWord(arrOfWords) {
  if (!arrOfWords.length) return null;

  //to start we take the first word as the longest one
  let largestWord = arrOfWords[0];

  // use for loop to go through the arrOfWords
  //     word is just a placeholder
  //        |
  for (let word of arrOfWords) {
    // if the current word is longer than the largestWord...
    if (word.length > largestWord.length) {
      // ... then that word becomes the new largestWord
      largestWord = word;
    }
  }
  return largestWord;
}

// Iteration #3: Calculate the sum

const numbers = [6, 12, 1, 18, 13, 16, 2, 1, 8, 10];

function sumNumbers(numbersArr) {
  if (!numbersArr) return null;
  let sum = 0;

  numbersArr.forEach( function (num) {
    sum += num;
  })

  // for (let el of numbersArr) {
  //   // we are adding "typeof" condition to reuse this function
  //   // to calculate sum of letters in the array of words

  //   // we can check the type of elements in the array:
  //   // console.log(`Type of el: ${typeof el}`);

  //   if (typeof el === 'string') sum += el.length;
  //   else sum += el;
  // }
  return sum;
}

// Iteration #3.1: Bonus

function sum(numbersArr) {
  if (!numbersArr) return null;
  let sum = 0;


  console.log('numbersArr', numbersArr)

  numbersArr.forEach( function (el) {
    if (typeof el === 'string') {
      sum += el.length;
    }
    else if (typeof el === 'object') {
      throw new Error("Unsupported data type sir or ma'am")
    } 
    else {
      sum += el
    };
  })

  return sum;
}






// Iteration #4: Calculate the average
// Level 1: Array of numbers
const numbersAvg = [2, 6, 9, 10, 7, 4, 1, 9];

function averageNumbers(arr) {
  var average = 0;
  var result = 0;
  if (arr.length === 0) {
    return null;
  }
  if (arr.length === 1) {
    return arr[0];
  }
  for (var i = 0; i < arr.length; i++) {
    result += arr[i];
  }
  average = result / arr.length;
  return average;
}


// Level 2: Array of strings
const wordsArr = ['seat', 'correspond', 'linen', 'motif', 'hole', 'smell', 'smart', 'chaos', 'fuel', 'palace'];
function averageWordLength(words) {
  if (!words.length) return null;
  let wordLengths = [];
  for (let word of words) {
    wordLengths.push(word.length);
  }
  return averageNumbers(wordLengths);
};

// the other way doing the same as above:
// const averageWordLength = words => {
//   if (!words.length) return null;
//   return words.join('').length / words.length;
// };

averageNumbers(wordsArr)



// Bonus - Iteration #4.1: A generic avg()
function avg(arr) {
  if (!arr.length) return null;
  else {
    var total = sum(arr) / arr.length;
    var totalFixed = Number(total.toFixed(2));
    return totalFixed;
  };

}

// Iteration #5: Unique arrays
const wordsUnique = [
  'crab',
  'poison',
  'contagious',
  'simple',
  'bring',
  'sharp',
  'playground',
  'poison',
  'communion',
  'simple',
  'bring'
];


const uniquifyArray = words => {
  if (!words.length) return null;
  let uniqueArr = [];

  words.forEach(function (word) {
    if (!uniqueArr.includes(word)) {
      uniqueArr.push(word)
    };
  })
  
  return uniqueArr;
};

// Second option - using Sets
// function uniquifyArray (words) {
//   var uniqueSet = new Set(words);   //  Create a set out of the array. Set is a list of unique values, only one of each value will be created in the Set.
//   var arr = [ ...uniqueSet ];      // Convert the Set to an array by spreading it (copying).

//   return arr;
// };

// Iteration #6: Find elements
const wordsFind = ['machine', 'subset', 'trouble', 'starting', 'matter', 'eating', 'truth', 'disobedience'];

function doesWordExist(arr, word) {
  if (!arr.length) return null;
  return arr.includes(word);
}



// Iteration #7: Count repetition
const wordsCount = [
  'machine',
  'matter',
  'subset',
  'trouble',
  'starting',
  'matter',
  'eating',
  'matter',
  'truth',
  'disobedience',
  'matter'
];

function howManyTimes(arr, word) {
  let count = 0;
  for (let el of arr) {
    if (el === word) count++;
  }
  return count;
}

// Iteration #8: Bonus

const matrix = [
  [8, 2, 22, 97, 38, 15, 0, 40, 0, 75, 4, 5, 7, 78, 52, 12, 50, 77, 91, 8],
  [49, 49, 99, 40, 17, 81, 18, 57, 60, 87, 17, 40, 98, 43, 69, 48, 4, 56, 62, 0],
  [81, 49, 31, 73, 55, 79, 14, 29, 93, 71, 40, 67, 53, 88, 30, 3, 49, 13, 36, 65],
  [52, 70, 95, 23, 4, 60, 11, 42, 69, 24, 68, 56, 1, 32, 56, 71, 37, 2, 36, 91],
  [22, 31, 16, 71, 51, 67, 63, 89, 41, 92, 36, 54, 22, 40, 40, 28, 66, 33, 13, 80],
  [24, 47, 32, 60, 99, 3, 45, 2, 44, 75, 33, 53, 78, 36, 84, 20, 35, 17, 12, 50],
  [32, 98, 81, 28, 64, 23, 67, 10, 26, 38, 40, 67, 59, 54, 70, 66, 18, 38, 64, 70],
  [67, 26, 20, 68, 2, 62, 12, 20, 95, 63, 94, 39, 63, 8, 40, 91, 66, 49, 94, 21],
  [24, 55, 58, 5, 66, 73, 99, 26, 97, 17, 78, 78, 96, 83, 14, 88, 34, 89, 63, 72],
  [21, 36, 23, 9, 75, 0, 76, 44, 20, 45, 35, 14, 0, 61, 33, 97, 34, 31, 33, 95],
  [78, 17, 53, 28, 22, 75, 31, 67, 15, 94, 3, 80, 4, 62, 16, 14, 9, 53, 56, 92],
  [16, 39, 5, 42, 96, 35, 31, 47, 55, 58, 88, 24, 0, 17, 54, 24, 36, 29, 85, 57],
  [86, 56, 0, 48, 35, 71, 89, 7, 5, 44, 44, 37, 44, 60, 21, 58, 51, 54, 17, 58],
  [19, 80, 81, 68, 5, 94, 47, 69, 28, 73, 92, 13, 86, 52, 17, 77, 4, 89, 55, 40],
  [4, 52, 8, 83, 97, 35, 99, 16, 7, 97, 57, 32, 16, 26, 26, 79, 33, 27, 98, 66],
  [88, 36, 68, 87, 57, 62, 20, 72, 3, 46, 33, 67, 46, 55, 12, 32, 63, 93, 53, 69],
  [4, 42, 16, 73, 38, 25, 39, 11, 24, 94, 72, 18, 8, 46, 29, 32, 40, 62, 76, 36],
  [20, 69, 36, 41, 72, 30, 23, 88, 34, 62, 99, 69, 82, 67, 59, 85, 74, 4, 36, 16],
  [20, 73, 35, 29, 78, 31, 90, 1, 74, 31, 49, 71, 48, 86, 81, 16, 23, 57, 5, 54],
  [1, 70, 54, 71, 83, 51, 54, 69, 16, 92, 33, 48, 61, 43, 52, 1, 89, 19, 67, 48]
];


const greatestProduct = matrix => {
  let product = 0;

  const numberOfRows = matrix.length;
  const numberOfColumns = matrix[0].length;

  // console.log(numberOfRows);
  // console.log(numberOfColumns)

  for (let i = 0; i < numberOfRows; i++) {
    let row = matrix[i];
    for (let e = 0; e < numberOfColumns - 3; e++) {
      // 0 - 1 - 2 - 3
      // 1 - 2 - 3 - 4
      let rowProduct = row[e] * row[e + 1] * row[e + 2] * row[e + 3];
      if (rowProduct > product) {
        product = rowProduct;
      }
    }
  }

  for (let i = 0; i < numberOfColumns; i++) {
    for (let e = 0; e < numberOfRows - 3; e++) {
      let columnProduct =
        matrix[e][i] * matrix[e + 1][i] * matrix[e + 2][i] * matrix[e + 3][i];
      if (columnProduct > product) {
        product = columnProduct;
      }
    }
  }

  return product;
};