JavaScriptIsomorphicStrings.md

JavaScript Isomorphic Strings

Challenge

Given two strings s and t, determine if they are isomorphic.

Two strings s and t are isomorphic if the characters in s can be replaced to get t.

All occurrences of a character must be replaced with another character while preserving the order of characters. No two characters may map to the same character, but a character may map to itself.

1^st Example

Input: s = 'egg', t = 'add'
Output: true

2^nd Example

Input: s = 'warm', t = 'cool'
Output: false

3^rd Example

Input: s = 'paper', t = 'title'
Output: true

Constraints

• 1 <= s.length <= 5 * 10⁴
• t.length == s.length
• s and t consist of any valid ascii character.

Solution

const isIsomorphic = (s, t) => {
    const hash1 = {},
          hash2 = {};

    for (let i = 0; i < s.length; i++) {
        if (hash1[s[i]] !== hash2[t[i]]) {
            return false;
        }

        hash1[s[i]] = i;

        hash2[t[i]] = i;
    }

    return true;
};

Explanation

I've created a function called isIsomorphic that takes in two strings s and t as parameters. Its purpose is to check if the two strings are isomorphic, meaning that each character in s can be replaced by a corresponding character in t while preserving the order of characters.

Inside the function, two empty objects called hash1 and hash2 are declared. These objects will be used to map characters from s and t, respectively.

The function then enters a loop that iterates through each character in s. The loop variable i represents the index of the current character.

Within the loop, it checks if the corresponding characters in s and t have different values in hash1 and hash2, respectively. If the values are different, it means that the characters are not isomorphic, so the function returns false immediately.

If the characters are isomorphic, the function updates values in hash1 and hash2 to be the index i.

After the loop ends, it means that all characters in s and t have been checked and found to be isomorphic. Therefore, the function returns true.

In summary, the isIsomorphic function checks if two strings are isomorphic by using two hash tables to map characters from each string and comparing their values. If any mismatch is found, it returns false, otherwise it returns true.

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