205. Isomorphic Strings

Description

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.

Constraints

Approach

Links

• GeeksforGeeks

• Leetcode

• ProgramCreek

• YouTube

Examples

Example 1

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

Output: true

Example 2

Example 3

Solutions

Solution 1

/**
 * Time complexity : 
 * Space complexity : 
 */

class Solution {
    public boolean isIsomorphic(String s, String t) {
        if(s.length() != t.length()) return false;
        
        Map<Character, Character> map = new HashMap();
        
        for(int i = 0; i < s.length(); i++) {
            char ch1 = s.charAt(i);
            char ch2 = t.charAt(i);
            
            if(map.containsKey(ch1)) {
                if(map.get(ch1) != ch2) return false;
            } else {
                map.put(ch1, ch2);
            }
        }
        
        Set<Character> values = new HashSet(map.values());
        if(values.size() == map.values().size()) {
            return true;
        }
        
        return false;
    }
}

Solution 2

Follow up