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.

Hash基本操作，对于每个元素放入对应的标号，如果不一致则返回false

var isIsomorphic = function(s, t) {    var h1 = {}    var h2 = {}    var count = 1    for(var i=0;i