Isomorphic strings

easyHash maps and sets target 15 min

Isomorphic strings

Not solved yetLeetCode 205. Isomorphic Strings

Two strings s and t have the same length. They are isomorphic (they have the same shape) when replacing the characters of s can turn it into t under two rules:

Every copy of a character gets the same replacement. If one a becomes x, every a becomes x.
Different characters get different replacements. If a becomes x, no other character can also become x.

All replacements happen at once, and a character may become itself: "abc" and "abd" are isomorphic, since a and b stay and c becomes d. Return True if s and t are isomorphic, and False otherwise.

Example 1

Inputs = "ball", t = "tree"OutputTrue

b becomes t, a becomes r, and l becomes e. Both copies of l become e.

Example 2

Inputs = "moon", t = "noon"OutputFalse

m would become n, and n would also stay n. Two different characters cannot become the same one.

Example 3

Inputs = "aab", t = "xyz"OutputFalse

The first a becomes x, so the second a must become x too, but it lines up with y.

Constraints

1 ≤ len(s) ≤ 5 × 10⁴
len(t) == len(s)
Characters can be any ASCII characters, including digits, spaces and punctuation.

Plan it first

Write a line for each before you code, then say them out loud. Compare with the Approach tab afterwards.

Walk In what order will you visit the input?Notebook What will you write down as you go?Promise What stays true after every step?Cost Time and space, in Big O.

Run examples checks the examples. Submit runs every test, including edge cases and, when the problem has one, a speed check on a large input.

Same pattern