leetcode [#205]

目录

• 1. 题目
• 2. 解决方案
• 3. 注意事项

题目

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
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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解决方案

import java.util.Hashtable;
public class Solution {
    public boolean isIsomorphic(String s, String t) {
        Hashtable<Character, Character> table = new Hashtable<>();
        for(int i = 0; i < s.length(); i++){
            if(!table.containsKey(s.charAt(i))){
                if(!table.containsValue(t.charAt(i))){
                    table.put(s.charAt(i), t.charAt(i));
                } else {
                    return false;
                }
            } else {
                if(table.get(s.charAt(i)) != t.charAt(i)) return false;
            }
        }
        return true;
    }
}

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注意事项

1. 思路类似290题，模式匹配，已存在的键必须对应相同的value，不同的键不能有相同的value。