Isomorphic Strings

Two equal-length strings are isomorphic if the characters of `s` can be replaced to get `t`, where every occurrence of a character maps to the same character and no two characters map to the same one. Return whether `s` and `t` are isomorphic. **Example 1:** ``` Input: s = "egg", t = "add" Output: true ``` **Example 2:** ``` Input: s = "foo", t = "bar" Output: false ``` **Example 3:** ``` Input: s = "paper", t = "title" Output: true ```