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Problem Solving Patterns

View Problem Solving Patterns files on GitHub.

Frequency counter

Anagrams

Given two strings, write a function to determine if the second string is an anagram of the first.

An anagram is a word, phrase or name formed by rearranging the letters of another, such as cinema, formed from iceman.

Understand the problem

• inputs - 2 strings
  • cases - numbers, null, undefined, spaces, empty
• output - true, false

Explore concrete examples

// Examples:
isAnagram('', ''); //true
isAnagram('azz', 'zaa'); //false
isAnagram('cinema', 'iceman'); //true
isAnagram('rat', 'car'); //false

Solution after breaking down, solving and refactoring

function validAnagram(str1, str2) {
    if (str1.length !== str2.length) {
        return false;
    }

    const countObj = {};

    for (let i = 0; i < str1.length; i++) {
        let letter = str1[i];

        countObj[letter] ? (countObj[letter] += 1) : (countObj[letter] = 1);
    }

    for (let i = 0; i < str2.length; i++) {
        let letter = str2[i];
        if (!countObj[letter]) {
            return false;
        } else {
            countObj[letter] -= 1;
        }
    }
    return true;
}

BigO is linear i.e. O(N)

Multiple pointers