205. Isomorphic Strings

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.

 

Approach #1: C++.

class Solution {
public:
    bool isIsomorphic(string s, string t) {
        int len = s.size();
        int ArrS[256] = {0};
        int ArrT[256] = {0};
        for (int i = 0; i < len; ++i) {          
            if (charArrS[s[i]] != charArrT[t[i]]) {
                return false;
            }
            ArrS[s[i]] = i + 1;
            ArrT[t[i]] = i + 1;
        }
        return true;
    }
};

　　

Approach #2: Java.

class Solution {
public:
    bool isIsomorphic(string s, string t) {
        int len = s.size();
        int ArrS[256] = {0};
        int ArrT[256] = {0};
        for (int i = 0; i < len; ++i) {          
            if (charArrS[s[i]] != charArrT[t[i]]) {
                return false;
            }
            ArrS[s[i]] = i + 1;
            ArrT[t[i]] = i + 1;
        }
        return true;
    }
};

　　

Approach #3: Python.

class Solution(object):
    def isIsomorphic(self, s, t):
        """
        :type s: str
        :type t: str
        :rtype: bool
        """
        arrS = {}
        arrT = {}
        
        for i, val in enumerate(s):
            arrS[val] = arrS.get(val, []) + [i]
            
        for i, val in enumerate(t):
            arrT[val] = arrT.get(val, []) + [i]
        
        return sorted(arrS.values()) == sorted(arrT.values())

　　

　　

Time Submitted	Status	Runtime	Language
a few seconds ago	Accepted	236 ms	python
5 minutes ago	Accepted	8 ms	java
13 minutes ago	Accepted	4 ms	cpp

Analysis: