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.
public class Solution { public boolean isIsomorphic(String s, String t) { if(s == t) return true; int len=s.length(); if(len==0) return true; HashMap<Character, Character> dict= new HashMap<Character,Character>(); for(int i = 0 ; i < len ; i++){ char sc = s.charAt(i); char tc = t.charAt(i); if(dict.containsKey(sc)){ if(dict.get(sc) != tc){ return false; } } else{ if(dict.containsValue(tc)){ return false; } else{ dict.put(sc,tc); } } } return true; } }
public class Solution { public boolean isIsomorphic(String s, String t) { int[] m1 = new int[256] ; int[] m2 = new int[256] ; int n = s.length(); for (int i = 0; i < n; ++i) { char sc = s.charAt(i); char tc = t.charAt(i); if (m1[sc] != m2[tc]) return false; m1[sc] = i + 1; m2[tc] = i + 1; } return true; } }