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
YouTube
Examples
Input: s = "egg", t = "add"
Output: true
Input: s = "foo", t = "bar"
Output: false
Input: s = "paper", t = "title"
Output: true
Solutions
/**
* 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;
}
}
/**
* Time complexity :
* Space complexity :
*/
class Solution {
public boolean isIsomorphic(String s, String t) {
if(s.length() != t.length()) return false;
int[] map = new int[256];
for(int i = s.length()-1; i >= 0; i--) {
int p1 = (int) s.charAt(i);
int p2 = (int) t.charAt(i);
if(map[p1] != map[p2+128]) {
return false;
} else {
map[p1] = i;
map[p2+128] = i;
}
}
return true;
}
}