Isomorphic Strings

Leetcode Problem 205: Isomorphic Strings

Problem Summary

Two strings s and t are isomorphic if there exists a consistent one-to-one character mapping from s to t — every occurrence of a character in s maps to the same character in t, and no two distinct characters in s map to the same character in t (though a character may map to itself).

Given two strings s and t of the same length, determine whether they are isomorphic.

Constraints:

• Both strings have the same length, between 1 and 50,000 characters.
• Both strings consist of any valid ASCII character.

Techniques

• Hash Table
• String

Solution

function isIsomorphic(s: string, t: string): boolean {
    let letterMappingS = new Map<string, string>()
    let letterMappingT = new Map<string, string>()

    for (let i = 0; i < s.length; i++) {
        if (letterMappingS.has(s.charAt(i)) && letterMappingS.get(s.charAt(i)) !== t.charAt(i)) {
            return false
        }

        if (letterMappingT.has(t.charAt(i)) && letterMappingT.get(t.charAt(i)) !== s.charAt(i)) {
            return false
        }

        letterMappingS.set(s.charAt(i), t.charAt(i))
        letterMappingT.set(t.charAt(i), s.charAt(i))
    }

    return true
}

console.log(isIsomorphic('egg', 'add'))