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Challenge: Valid Anagrams

Instructions

Write a function called validAnagrams that takes in two strings and determines whether they are valid anagrams of each other. An anagram is a word or phrase formed by rearranging the letters of a different word or phrase, typically using all the original letters exactly once.

Function Signature

/**
 * Determines whether two strings are valid anagrams.
 * @param {string} str1 - The first string.
 * @param {string} str2 - The second string.
 * @returns {boolean} - True if the strings are valid anagrams, false otherwise.
 */
function validAnagrams(str1: string, str2: string): boolean;

Examples

validAnagrams('listen', 'silent'); // true
validAnagrams('hello', 'world'); // false
validAnagrams('astronomer', 'moonstarer'); // true

Hints

• Split the strings into arrays of characters, then reduce each array into an object of character frequencies for the strings
• Compare the frequencies

Solutions

Click For Solution

function validAnagrams(str1, str2) {
  const freqCount1 = str1.split('').reduce((acc, char) => {
    acc[char] = (acc[char] || 0) + 1;
    return acc;
  }, {});

  const freqCount2 = str2.split('').reduce((acc, char) => {
    acc[char] = (acc[char] || 0) + 1;
    return acc;
  }, {});

  return Object.keys(freqCount1).every(
    (char) => freqCount1[char] === freqCount2[char]
  );
}

Explanation

• Create a variable freqCount1 and assign it to the result of calling reduce on str1.split(''). This will create an object that contains the frequency count of each character in str1. For example, validAnagrams('listen', 'silent') will return { l: 1, i: 1, s: 1, t: 1, e: 1, n: 1 } for freqCount1.
• Do the same for freqCount2 and assign it to the result of calling reduce on str2.split(''). This will create an object that contains the frequency count of each character in str2.
• Object.keys will check if every character in freqCount1 has the same frequency count in freqCount2. If all of the frequency counts are equal, every will return true. If any of the frequency counts are not equal, every will return false and we will know that the strings are not valid anagrams.

Test Cases

test('Checking for Valid Anagrams', () => {
  expect(validAnagrams('listen', 'silent')).toBe(true);
  expect(validAnagrams('hello', 'world')).toBe(false);
  expect(validAnagrams('astronomer', 'moonstarer')).toBe(true);
  expect(validAnagrams('apple', 'banana')).toBe(false);
});