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 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.

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其实用HashMap就好，可惜当年刚开始写不知道这玩意啊……就是每读一个s字母，就去找相对应的t中的字母，如果没找到就存起来，找到了就和已经存的比较，有冲突就报错就好。

public class Solution {
<span style="white-space:pre">	</span>public boolean isIsomorphic(String s, String t) {
<span style="white-space:pre">		</span>int[] a = new int[200];
<span style="white-space:pre">		</span>int[] b = new int[200];
<span style="white-space:pre">		</span>int s1 = 0;
<span style="white-space:pre">		</span>int s2 = 0;

<span style="white-space:pre">		</span>for (s1 = 0; s1 < s.length(); s1++) {
<span style="white-space:pre">			</span>if (a[s.charAt(s1) - ' '] == 0) {
<span style="white-space:pre">				</span>a[s.charAt(s1) - ' '] = t.charAt(s1) - ' ';
<span style="white-space:pre">				</span>continue;
<span style="white-space:pre">			</span>}
<span style="white-space:pre">			</span>if (a[s.charAt(s1) - ' '] != t.charAt(s1) - ' ')
<span style="white-space:pre">				</span>return false;
<span style="white-space:pre">		</span>}
<span style="white-space:pre">		</span>for (s1 = 0; s1 < t.length(); s1++) {
<span style="white-space:pre">			</span>if (b[t.charAt(s1) - ' '] == 0) {
<span style="white-space:pre">				</span>b[t.charAt(s1) - ' '] = s.charAt(s1) - ' ';
<span style="white-space:pre">				</span>continue;
<span style="white-space:pre">			</span>}
<span style="white-space:pre">			</span>if (b[t.charAt(s1) - ' '] != s.charAt(s1) - ' ')
<span style="white-space:pre">				</span>return false;
<span style="white-space:pre">		</span>}
<span style="white-space:pre">		</span>return true;
<span style="white-space:pre">	</span>}
}