2020-programming-challenges.js

//Mock interview
//reverse sentence

const reverseSentence = str => {
  if (typeof str !== "string" || !str.length) {
    return null;
  }
  const smallStr = str
    .toLowerCase()
    .split("")
    .reverse()
    .join("");

  return smallStr;
};

//tests
console.log(reverseSentence("") === null);
console.log(reverseSentence(123) === null);
console.log(reverseSentence([1, 2, 3, 4]) === null);
console.log(reverseSentence("smart work") === "krow trams");
console.log(reverseSentence("good job") === "boj doog");
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const operationAnagram = (str1, str2) => {
  if (
    typeof str1 !== "string" ||
    typeof str2 !== "string" ||
    !str1.length ||
    !str2.length
  ) {
    return null;
  }

  const input1 = str1.split("");
  const count1 = {};
  const input2 = str2.split("");
  const count2 = {};

  input1.forEach(item => {
    if (count1[item]) {
      count1[item] = count1[item] + 1;
    } else {
      count1[item] = 1;
    }
  });

  input2.forEach(item => {
    if (count2[item]) {
      count2[item] = count2[item] + 1;
    } else {
      count2[item] = 1;
    }
  });

  const key1 = Object.keys(count1);
  for (let key of key1) {
    if (count1[key] !== count2[key]) {
      return false;
    }
  }
  return true;
};

//tests

console.log(operationAnagram("cheerios", "") === null, "test 1");
console.log(operationAnagram("", "cake") === null, "test 2");
console.log(operationAnagram("kite", "apple") === false, "test 3");
console.log(operationAnagram("mary", "army") === true, "test 4");

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//Anagram challenge

const isAnagram = (str1, str2) => {
  if (
    typeof str1 !== "string" ||
    typeof str2 !== "string" ||
    !str1.length ||
    !str2.length
  ) {
    return null;
  }
  const result1 = str1
    .toLowerCase()
    .split("")
    .sort()
    .join("");
  const result2 = str2
    .toLowerCase()
    .split("")
    .sort()
    .join("");
  if (result1.length !== result2.length) {
    return false;
  }
  if (result1 !== result2) {
    return false;
  }
  return true;
};

//tests
console.log(isAnagram("cheerios", "") === null, "test 1");
console.log(isAnagram("", "cake") === null, "test 2");
console.log(isAnagram("kite", "apple") === false, "test 3");
console.log(isAnagram("mary", "army") === true, "test 4");

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//find the largest array from an array of arrays

const twoDimArr = arr => {
  let largest = [];
  let num;
  for (let i = 0; i < arr.length; i++) {
    for (let j = 0; j < arr[i].length; j++) {
      num = Math.max(...arr[i]);
    }
    largest.push(num);
  }
  return largest;
};

//tests

console.log(
  twoDimArr([
    [1, 2, 3],
    [4, 5, 6],
    [7, 8, 9],
    [10, 11, 12],
    [13, 14, 15]
  ])
);

//Confirm ending

const confirmEnding = (str, target) => {
  if (
    typeof str !== "string" ||
    typeof target !== "string" ||
    !str.length ||
    !target.length
  ) {
    return false;
  }
  const words = str.split("");
  if (target === words[words.length - 1]) {
    return true;
  } else {
    return false;
  }
};

//tests

console.log(confirmEnding("pancakes", "") === false, "test 1");
console.log(confirmEnding("", "m") === false, "test 2");
console.log(confirmEnding("", "") === false, "test 3");
console.log(confirmEnding("maple", "e") === true, "test 4 ");
console.log(confirmEnding("tuna", "a") === true, "test 5");

//Another method

const confirmEnd = (str, target) => {
  if (str.endsWith(target)) {
    return true;
  } else {
    return false;
  }
};

//tests

console.log(confirmEnd("maple", "e") === true, "test extra 1 ");
console.log(confirmEnd("tunafish", "h") === true, "test extra 2");
console.log(confirmEnd("misosoup", "h") === false, "test extra 2");

//Repeat string num times

const repeatNumTimes = (str, num) => {
  if (
    typeof str !== "string" ||
    !str.length ||
    !Number.isFinite(num) ||
    num < 0
  ) {
    return false;
  }
  let final = "";
  for (let i = 0; i < num; i++) {
    final = final + str;
  }
  return final;
};

//tests

console.log(repeatNumTimes("", 3) === false, "test 1");
console.log(repeatNumTimes("abc", -1) === false, "test 2");
console.log(repeatNumTimes("xyz", 2) === "xyzxyz", "test 3");
console.log(repeatNumTimes("we won", 2) === "we wonwe won", "test 4");

//alternate method

const repeatNtimes = (str, num) => {
  return str.repeat(num);
};

//tests
console.log(repeatNtimes("xyz", 3) === "xyzxyzxyz", "test extra 1");

//Truncate string
//Truncate a string (first argument) if it is longer than the given
//maximum string length (second argument). Return the truncated string with
//a ... ending, else return string.

const truncateString = (str, num) => {
  if (
    typeof str !== "string" ||
    !str.length ||
    !Number.isFinite(num) ||
    num < 0
  ) {
    return false;
  }
  if (str.length <= num) {
    return str;
  } else {
    return str.slice(0, num - 3) + "...";
  }
};

//tests
console.log(truncateString("", 6) === false);
console.log(truncateString("shilpi", -3) === false);
console.log(truncateString("shilpi", 6) === "shilpi");
console.log(truncateString("hey whats up", 5) === "he...");

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//18-09-2020, Thursday

//Find out whether given series is a AP or not

const mathSequenceAP = arr => {
  if (!Array.isArray(arr) || !arr.length) {
    return null;
  }
  for (let i = 1; i < arr.length - 1; i++) {
    if (arr[i] - arr[i - 1] !== arr[i + 1] - arr[i]) {
      return false;
    }
  }
  return true;
};

//tests

console.log(mathSequenceAP(1, 2, 3, 4, 5, 6) === null, "test 1");
console.log(mathSequenceAP("It's a trap") === null, "test 2");
console.log(mathSequenceAP([]) === null, "test 3");
console.log(mathSequenceAP([2, 4, 6, 8]) === true, "test 4");
console.log(mathSequenceAP([2, 4, 6, 9]) === false, "test 5");
console.log(mathSequenceAP([2, 3, 6, 8]) === false, "test 6");

//Reverse a string

const reverseString = str => {
  if (typeof str !== "string" || !str.length) {
    return null;
  }
  const results = [];
  const strSplit = str.split("");
  for (let i = strSplit.length - 1; i >= 0; i--) {
    results.push(strSplit[i]);
  }
  return results.join("");
};

//tests

console.log(reverseString("") === null, "test 1");
console.log(reverseString(123) === null, "test 2");
console.log(reverseString("hello") === "olleh", "test 3");
console.log(reverseString("shilpi") === "iplihs", "test 4");
console.log(reverseString("sweet") === "teews", "test 5");

//tutorial's method

const stringReverse = str => {
  return str
    .split("")
    .reverse()
    .join("");
};

//Another way

const strReverse = str => {
  let results = "";
  for (let i = str.length - 1; i >= 0; i--) {
    results = results + str[i];
  }
  return results;
};

//Factorial

const factorial = num => {
  if (!Number.isInteger(num)) {
    return null;
  }
  let results = 1;
  for (let i = num; i >= 1; i--) {
    results = results * i;
  }
  return results;
};

//tests

console.log(factorial("string") === null, "test 1");
console.log(factorial([1, 2, 3, 4]) === null, "test 2");
console.log(factorial(3) === 6, "test 3");
console.log(factorial(6) === 720, "test 4");

//Palindrome

const palindrome = str => {
  if (typeof str !== "string" || !str.length) {
    return null;
  }
  const smallStr = str.toLowerCase().replace(/[\W_]/, "");
  const reverseStr = smallStr
    .split("")
    .reverse()
    .join("");
  if (smallStr === reverseStr) {
    return true;
  } else {
    return false;
  }
};

//tests

console.log(palindrome(123) === null, "test 1");
console.log(palindrome("") === null, "test 2");
console.log(palindrome("eye") === true, "test 3");
console.log(palindrome("shilpi") === false, "test 4");
console.log(palindrome("level") === true, "test 5");
console.log(palindrome("race car") === true, "test 6");

//Longest word length

const LongestWordLength = str => {
  if (typeof str !== "string" || !str.length) {
    return null;
  }
  const longestWord = str.split(" ");
  let longest = "";
  for (let i = 0; i < longestWord.length; i++) {
    if (longestWord[i].length > longest.length) {
      longest = longestWord[i];
    }
  }
  return longest.length;
};
//tests

console.log(LongestWordLength("") === null, "test 1");
console.log(LongestWordLength(123) === null, "test 2");
console.log(LongestWordLength("my name is shilpi") === 6, "test 3");
console.log(LongestWordLength("cats are awesome") === 7, "test 4");
console.log(LongestWordLength("wishing well") === 7, "test 5");

//tutorial

const longestWord = str => {
  return str.split(" ").sort(function(a, b) {
    return b.length - a.length;
  })[0].length;
};

//19-09-2020, Friday

//Title case a sentence

const titleCase = str => {
  if (typeof str !== "string" || !str.length) {
    return null;
  }
  const smallStr = str.toLowerCase().split(" ");
  for (let i = 0; i < smallStr.length; i++) {
    smallStr[i] = smallStr[i][0].toUpperCase() + smallStr[i].slice(1);
  }
  return smallStr.join(" ");
};

//test cases

console.log(titleCase("Shilpi christy"));
console.log(titleCase(123) === null, "test 1");
console.log(titleCase("") === null, "test 2");
console.log(titleCase("my name is Shilpi") === "My Name Is Shilpi", "test 3");
console.log(titleCase("flying kites") === "Flying Kites", "test 4");
console.log(titleCase("Organic farming") === "Organic Farming", "test 5");

//Another way

const caseTitle = str => {
  return str
    .toLowerCase()
    .split(" ")
    .map(item => {
      return item[0].toUpperCase() + item.slice(1);
    })
    .join(" ");
};

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//Older Challenges

//Programming practice

//write a js program to check two numbers and return true is one of them is
//100 or their sum is 100

const isHundred = (num1, num2) => {
  if (typeof num1 !== "number" || typeof num2 !== "number" || !num1 || !num2) {
    return null;
  }
  if (num1 === 100 || num2 === 100 || num1 + num2 === 100) {
    return true;
  } else {
    return false;
  }
};

//0(1)

//tests

console.log(isHundred(100, 1) === true);
console.log(isHundred(1, 100) === true);
console.log(isHundred(10, 19) === false);
console.log(isHundred(15, 75) === false);
console.log(isHundred(50, 50) === true);
console.log(isHundred(1, "shilpi") === null);
console.log(isHundred(1) === null);

//Write a program to get the extension of a filename

const getFileExtension = str => {
  if (
    typeof str !== "string" ||
    str.lastIndexOf(".") === str.length - 1 ||
    str.lastIndexOf(".") === -1
  ) {
    return null;
  }
  const result = str.slice(str.lastIndexOf("."));
  return result;
};

//tests

console.log(getFileExtension("index.html") === ".html");
console.log(getFileExtension("index.css") === ".css");
console.log(getFileExtension("index.js") === ".js");
console.log(getFileExtension("index") === null);
console.log(getFileExtension("index.") === null);
console.log(getFileExtension(123) === null);

// write a program in js that replace every character in a given string with
// the character following it in a alphabet

const moveCharacterForword = str => {
  if (typeof str !== "string" || !str.length) {
    return null;
  } else {
    return str
      .split("")
      .map(char => String.fromCharCode(char.charCodeAt(0) + 1))
      .join("");
  }
};

//tests

console.log(moveCharacterForword("abc") === "bcd", "test 1");
console.log(moveCharacterForword("") === null, "test 2");
console.log(moveCharacterForword(123) === null, "test 3");

//write a js program to return a current date

const formatDate = (date = new Date()) => {
  const day = date.getDate();
  const month = date.getMonth();
  const year = date.getFullYear();
  return `${day}/${month}/${year}`;
};

console.log(formatDate());
const now = new Date();
console.log(now);

//Write a js program to create a new string adding "New!" in front of
//a new given string , if the given string already has "New!" return the
//original string

const addingNew = str => {
  if (typeof str !== "string" || !str.length) {
    return null;
  }
  const newStr = str.split(" ");
  if (newStr[0] === "New!") {
    return str;
  } else {
    return newStr.splice(0, 0, "New!").join(" ");
  }
};

//tests

console.log(addingNew("name is shilpi") === "New! name is shilpi");
console.log(addingNew(123) === null);
console.log(addingNew("") === null);
console.log(addingNew("New! offers") === "New! offers");

//alternate method

const addNew = string =>
  string.indexOf("New!" === 0) ? string : `New! ${string}`;

//tests

console.log(addNew("Discounts"));
console.log(addNew("New! offers"));

Hey bhaiya....i need some help in this program. Its not working.
const addingNew = str => {
if (typeof str !== "string" || !str.length) {
return null;
}
const newStr = str.split(" ");
if (newStr[0] === "New!") {
return str;
} else {
return newStr.splice(0, 0, "New!").join(" ");
}
};

//tests

console.log(addingNew("name is shilpi") === "New! name is shilpi");

Suggestions:

1. Please write code with syntax highlighting like js your code . Otherwise, code is really difficult to read.
2. Line#111: string.indexOf("New!") === 0, not string.indexOf("New!" === 0)
3. Line#7: Suggestion Number.isFinite() or Number.isInteger()
4. For running tests, can use code block like this:

const testCases = [
  { input: 6, output: 8 },
  { input: 1, output: 1 },
  { input: 9, output: 34 },
];

testCases.forEach(({ input, output }, index) => {
  console.log(`test ${index}: ${fib(input) === output ? "Succeed" : "Failed"}`);
});