leetcode--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 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.

[java] view plain copy

1. import java.util.Arrays;  
2. public class Solution {  
3.     public boolean isIsomorphic(String s, String t) {  
4.         if(s.length()!=t.length()) return false;  
5.         int[] map1 = new int[257];    
6.         int[] map2 = new int[257];        
7.         Arrays.fill(map1, -1);  
8.         Arrays.fill(map2, -1);  
9.         for(int i=0;i<s.length();i++){  
10.             if(map1[s.charAt(i)]==-1){  
11.                 map1[s.charAt(i)] = t.charAt(i);  
12.             }else{  
13.                 if(map1[s.charAt(i)] != t.charAt(i)){  
14.                     return false;  
15.                 }  
16.             }  
17.             if(map2[t.charAt(i)]==-1){  
18.                 map2[t.charAt(i)] = s.charAt(i);  
19.             }else{  
20.                 if(map2[t.charAt(i)] != s.charAt(i)){  
21.                     return false;  
22.                 }  
23.             }  
24.         }         
25.         return true;  
26.     }  
27. } 

原文链接http://blog.csdn.net/crazy__chen/article/details/45439841