Check if two given strings are isomorphic to each other
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.
Given "egg", "add", return true.
Given "foo", "bar", return false.
Given "paper", "title", return true.