# 算法：同构字符串205. Isomorphic Strings

2020/12/14 23:46:04

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# 题目

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.

Example 1:

``````Input: s = "egg", t = "add"
Output: true
``````

Example 2:

``````Input: s = "foo", t = "bar"
Output: false
``````

Example 3:

``````Input: s = "paper", t = "title"
Output: true
``````

Note:
You may assume both s and t have the same length.

# 解法

``````package hashtable;

// https://leetcode.com/problems/isomorphic-strings/

import java.util.HashMap;
import java.util.Map;

public class IsomorphicStrings {

public boolean isIsomorphic(String s, String t) {

// check edge
if (s == null || t == null) {

return s == t;
}
int len = s.length();
if (len != t.length()) {

return false;
}

Map<Character, Integer> smap = new HashMap<>();
Map<Character, Integer> tmap = new HashMap<>();
for (Integer i = 0; i < len; i++) {

char sc = s.charAt(i);
char tc = t.charAt(i);

if (smap.get(sc) != tmap.get(tc)) {

return false;
}
}

return true;
}

private void addItem(Map<Character, Integer> map, Integer i, char c) {

if (!map.containsKey(c)) {

map.put(c, i);
}
}
}
``````