LeetCode [205] Isomorphic Strings

 205. Isomorphic Strings

Easy

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.

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class Solution { public: bool isIsomorphic(string s, string t) { int ns = s.size(), nt = t.size(); if(ns!=nt) return false; unordered_map<char, char> hash1, hash2; for(int i=0; i<ns; ++i){ if(hash1.count(s[i])>0 && hash1[s[i]]!=t[i]) return false; hash1[s[i]] = t[i]; if(hash2.count(t[i])>0 && hash2[t[i]]!=s[i]) return false; hash2[t[i]] = s[i]; } return true; } };

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class Solution { Map<Character, Character> map1 = new HashMap<>(); Map<Character, Character> map2 = new HashMap<>(); public boolean isIsomorphic(String s, String t) { for(int i=0; i<s.length(); ++i){ char c1 = s.charAt(i), c2 = t.charAt(i); if(!map1.containsKey(c1)) map1.put(c1, c2); if(!map2.containsKey(c2)) map2.put(c2, c1); if(map1.get(c1)!=c2 || map2.get(c2)!=c1) return false; } return true; } }