isomorphic-strings.js

// Given two strings s and t, determine if they are isomorphic.
//
// Two strings 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.
//
// For example,
// Given "egg", "add", return true.
//
// Given "foo", "bar", return false.
//
// Given "paper", "title", return true.
//
// Note:
// You may assume both s and t have the same length.


/**
 * @param {string} s
 * @param {string} t
 * @return {boolean}
 */
var isIsomorphic = function(s, t) {
    const hashMapS = {};
    const hashMapT = {};
    for (var i = 0, l = s.length; i < l; i++) {
        var sc = s.charAt(i);
        var tc = t.charAt(i);
        if (hashMapS[sc] === undefined && hashMapT[tc] === undefined) {
            hashMapS[sc] = tc;
            hashMapT[tc] = sc;
        } else if (hashMapS[sc] !== tc) {
            return false;
        }
    }
    return true;
};