Isomorphic Strings

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:

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

Constraints:

• 1 <= s.length <= 5 * 104
• t.length == s.length
• s and t consist of any valid ascii character.

Code

其實就是 Word Pattern，code 直接複製貼上稍微改一下就 AC了。

class Solution {
public:
    bool isIsomorphic(string s, string t) {
 
        if(s.size() != t.size()) return false;
 
        unordered_map<char, int> pti;
        unordered_map<char, int> sti;
        for(int i = 0; i < s.size(); i++) {
            if(pti[s[i]] != sti[t[i]]) return false;
            // default is 0 if key not exist!
            pti[s[i]] = i + 1;
            sti[t[i]] = i + 1;
        }
 
        return true;
    }
};

Link

• Isomorphic Strings