205. Isomorphic Strings

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205. Isomorphic Strings

Description

Given two strings s and t, determine if they are isomorphic.

Two strings s and t 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:

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Input: s = "egg", t = "add"

Output: true

Explanation:

The strings s and t can be made identical by:

  • Mapping 'e' to 'a'.
  • Mapping 'g' to 'd'.

Example 2:

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Input: s = "foo", t = "bar"

Output: false

Explanation:

The strings s and t can not be made identical as 'o' needs to be mapped to both 'a' and 'r'.

Example 3:

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Input: s = "paper", t = "title"

Output: true

Constraints:

  • 1 <= s.length <= 5 * 10^4
  • t.length == s.length
  • s and t consist of any valid ascii character.

Hints/Notes

Solution

Language: C++

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class Solution {
public:
    bool isIsomorphic(string s, string t) {
        int m = s.size(), n = t.size();
        if (m != n) {
            return false;
        }
        unordered_map<char, char> mapping;
        unordered_set<char> mapped;
        for (int i = 0; i < n; i++) {
            if (mapping.contains(s[i]) && mapping[s[i]] != t[i]) {
                return false;
            }
            if (!mapping.contains(s[i]) && mapped.contains(t[i])) {
                return false;
            }
            mapping[s[i]] = t[i];
            mapped.insert(t[i]);
        }
        return true;
    }
};