Skip to content

205. Isomorphic Strings 👍

  • Time: $O(n)$
  • Space: $O(128) = O(1)$
 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
class Solution {
 public:
  bool isIsomorphic(string s, string t) {
    vector<int> charToIndex_s(128);
    vector<int> charToIndex_t(128);

    for (int i = 0; i < s.length(); ++i) {
      if (charToIndex_s[s[i]] != charToIndex_t[t[i]])
        return false;
      charToIndex_s[s[i]] = i + 1;
      charToIndex_t[t[i]] = i + 1;
    }

    return true;
  }
};

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
class Solution {
  public boolean isIsomorphic(String s, String t) {
    Map<Character, Integer> charToIndex_s = new HashMap<>();
    Map<Character, Integer> charToIndex_t = new HashMap<>();

    for (Integer i = 0; i < s.length(); ++i)
      if (charToIndex_s.put(s.charAt(i), i) != charToIndex_t.put(t.charAt(i), i))
        return false;

    return true;
  }
}

1
2
3
class Solution:
  def isIsomorphic(self, s: str, t: str) -> bool:
    return [*map(s.index, s)] == [*map(t.index, t)]