Isomorphic Strings

Question

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.

Tags

• Array
• Hashmap

Thought

Use two hash map two describe the mapping relation between the characters in these two string.

Code

class Solution(object):
    def isIsomorphic(self, s, t):
        """
        :type s: str
        :type t: str
        :rtype: bool
        """
        sourceMap, targetMap = dict(), dict()
        for i in xrange(len(s)):
            source = sourceMap.get(t[i], None)
            target = targetMap.get(s[i], None)
            if source is None and target is None:
                sourceMap[t[i]] = s[i]
                targetMap[s[i]] = t[i]
            elif source != s[i] or target != t[i]:
                return False
        return True