[LeetCode 205] Isomorphic Strings

Given two strings s and t, determine if they are isomorphic.

Two strings are isomorphic if the characters in s can be replaced to gett.

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.

soluton:

By definition, probably we should use hashmap to store the mapping rule.

construct the map from the begin of string, then compare if later character follow the rules.

two case will violate the rule: 1. same character maps to different ones 2. different character map to same one

public boolean isIsomorphic(String s, String t) {
        if(s.length() != t.length()) return false;
        if(s.length() <=1) return true;
        Map<Character, Character> dic = new HashMap<Character, Character>();
        for(int i=0; i<s.length(); i++) {
            char s1 = s.charAt(i);
            char t1 = t.charAt(i);
            if(!dic.containsKey(s1)) {
                if(dic.containsValue(t1)) return false;
                else dic.put(s1, t1);
            }
            else {
                if(!dic.get(s1).equals(t1)) return false;
            }
        }
        return true;
    }

[LeetCode 205] Isomorphic Strings

原文：http://blog.csdn.net/sbitswc/article/details/48702317