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.
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
Note:
You may assume both s and t have the same length.