lab-func-arrays-solution.js

// updated: 01/24/2020
// https://github.com/ironhack-labs/lab-javascript-functions-and-arrays

// ***********************************************************************************************
// Iteration #1: Find the maximum
// ***********************************************************************************************

function maxOfTwoNumbers(num1, num2) {
  if (num1 > num2) {
    return num1;
  } else {
    return num2;
  }
}

// es6 & ternary conditional
// const maxOfTwoNumbers = (a, b) => (a > b ? a : b);

// ***********************************************************************************************
// Iteration #2: Find longest word
// ***********************************************************************************************

const words = ['mystery', 'brother', 'aviator', 'crocodile', 'pearl', 'orchard', 'crackpot'];

function findLongestWord(arrOfWords) {
  if (!arrOfWords.length) {
    return null;
  }
  
  if (arrOfWords.length === 1) {
    return arrOfWords[0];
  }
  
  //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];

// SOLUTION WITHOUT BONUS:
function sumNumbers(numbers) {
  if (numbers.length === 0) {
    return 0;
  }
  
  let temp = 0;
  
  for (let number of numbers) {
    temp += number;
  }
  
  return temp;
}

// SOLUTION WITH BONUS
function sum(someArr) {
  if (!someArr) {
    return 0;
  }
  
  let sum = 0;
  
  for (let el of someArr) {
    if (typeof el === 'object') {
      throw new Error("Unsupported data type sir or ma'am");
      return;
    }
    
    // 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 #4: Calculate the average
// ***********************************************************************************************

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

// manual solution:
// function averageNumbers (numbers) {
//   if (!numbers.length) return null;
//   let temp = 0;
//   for (let number of numbers) {
//     temp += number;
//   }
//   return temp / numbers.length;
// };

// cleaner solution:
function averageNumbers(numbers) {
  if (!numbers.length) {
    return null;
  } else {
    return sumNumbers(numbers) / numbers.length;
  }
  
  // the same as above, to avoid if-else:
  // return sumNumbers(numbers) / numbers.length || null;
}

// one line solution:
// const averageNumbers = numbers => !numbers ? null : sumNumbers(numbers) / numbers.length;

// Level 2: Array of strings
const wordsArr = ['seat', 'correspond', 'linen', 'motif', 'hole', 'smell', 'smart', 'chaos', 'fuel', 'palace'];

// super manual solution:
// 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;
};

// BONUS:

function avg(arr) {
  if (arr.length === 0) {
    return null;
  }
  
  const avgValue = (sum(arr) / arr.length).toFixed(2);

  return Number(avgValue);
}

// ***********************************************************************************************
// 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 = [];
  
  //   for (let i = 0; i < words.length; i++) {
  //     let word = words[i];
  //     // indexOf() => returns 1 (true) if the word already exists in the array
  //     // indexOf() => returns -1 (false) if the word doesn't exist in the array
  //     if (uniqueArr.indexOf(word) < 0) {
  //       uniqueArr.push(word);
  //     }
  //   }

  for (let word of words) {
  
    if (!uniqueArr.includes(word)) {
       uniqueArr.push(word);
    }
    
  }
  
  return uniqueArr;
};

// solution using Set:
// const uniquifyArray = words => [ ...new Set(words) ];

// ***********************************************************************************************
// Iteration #6: Find elements
// ***********************************************************************************************

const wordsFind = ['machine', 'subset', 'trouble', 'starting', 'matter', 'eating', 'truth', 'disobedience'];

// super manual solution:
// function doesWordExist(someArr, someWord) {
// if (arr.length === 0) return null;
//   let doesExist = false;
//   for(let i=0; i<someArr.length; i++){
//     if(someArr[i] === someWord){
//       doesExist = true;
//     }
//   }
//   return doesExist;
// }

// better then above:
// function doesWordExist(arr, word){
// if (arr.length === 0) return null;
//   for (let el of arr){
//     if (el === word) return true;
//   }
//   return false;
// }

// the shortest and the cleanest:
function doesWordExist(arr, word) {
  if (arr.length === 0) {
    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]
];

// borrowed solution, needs check - passes tests
function greatestProduct(matrix) {
  let finalProduct = 0;

  const rowsCount = matrix.length;
  const columnsCount = matrix[0].length;

  // console.log(rowsCount);
  // console.log(columnsCount)

  for (let i = 0; i < rowsCount; i++) {
    let row = matrix[i];
    for (let x = 0; x < columnsCount - 3; x++) {
      // 0 - 1 - 2 - 3
      // 1 - 2 - 3 - 4
      let rowProduct = row[x] * row[x + 1] * row[x + 2] * row[x + 3];
      if (rowProduct > finalProduct) {
        finalProduct = rowProduct;
      }
    }
  }

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

  return finalProduct;
}