LeetCode: Isomorphic Strings

Written by Stephanie Segura | March 31, 2021

Stephanie Segura
2 min readMar 31, 2021

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Taking a look at another Algorithm this week, we’re tackling Isomorphic Strings. What are they and how in the world can we determine if the strings we have are Isomorphic or not? Let’s look at the definition below and get started:

“Two strings, X and Y , are called isomorphic if all occurrences of each character in X can be replaced with another character to get Y and vice-versa. For example, consider strings ACAB and XCXY .”



Please click the link below to view the Problem Statement


My solution was the following:

Although my solution worked, it was not very fast on the time complexity spectrum. As always, here is a faster, optimal, one liner solution.

Using the spread operator, mapping through each element of the string and comparing the index to the other string. Genius!


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