1import java.util.HashMap;
2
3public class IsomorphicStrings {
4    public boolean isIsomorphic(String s, String t) {
5        HashMap<Character, Character> map_s = new HashMap<>();
6        HashMap<Character, Character> map_t = new HashMap<>();
7        for (int i = 0; i < s.length(); ++i) {
8            char sc = s.charAt(i);
9            char tc = t.charAt(i);
10            if (map_s.containsKey(sc) && map_s.get(sc) != tc ||
11                map_t.containsKey(tc) && map_t.get(tc) != sc)
12                return false;
13            map_s.put(sc, tc);
14            map_t.put(tc, sc);
15        }
16        return true;
17    }
18}

1using System;
using System.Collections.Generic;

public class Solution {
    private List<int> GeneratePattern(string s) {
        Dictionary<char, int> map = new Dictionary<char, int>();
        List<int> pattern = new List<int>();
        int engine = 1;
        foreach (char c in s) {
            if (!map.ContainsKey(c)) {
                map[c] = engine++;
            }
            pattern.Add(map[c]);
        }
        return pattern;
    }

    public bool IsIsomorphic(string s, string t) {
        return GeneratePattern(s).SequenceEqual(GeneratePattern(t));
    }
}