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IsomorphicStrings.java
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IsomorphicStrings.java
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package string;
import java.util.HashMap;
import java.util.Map;
/**
* Created by gouthamvidyapradhan on 11/04/2018.
* 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.
Solution O(N): Maintain two hashmaps and compare character by character.
*/
public class IsomorphicStrings {
/**
* Main method
* @param args
* @throws Exception
*/
public static void main(String[] args) throws Exception{
System.out.println(new IsomorphicStrings().isIsomorphic("abc", "dea"));
}
public boolean isIsomorphic(String s, String t) {
if(s.length() != t.length()) return false;
Map<Character, Character> first = new HashMap<>();
Map<Character, Character> second = new HashMap<>();
for(int i = 0; i < s.length(); i ++){
char c = s.charAt(i);
if(first.containsKey(c)){
char secondC = first.get(c);
if(t.charAt(i) != secondC) return false;
} else{
first.put(c, t.charAt(i));
if(second.containsKey(t.charAt(i))) return false;
second.put(t.charAt(i), c);
}
}
return true;
}
}