algorithm/Java
1
0
Fork 0
mirror of https://github.com/TheAlgorithms/Java.git synced 2025-12-19 07:00:35 +08:00
Code Issues Packages Projects Releases Wiki Activity

refactor: refactoring and documenting Isomorphic String Checker (#6359)

Browse Source 
refactor: refactoring and documenting Isomorphic String Checker

Co-authored-by: Deniz Altunkapan <93663085+DenizAltunkapan@users.noreply.github.com>
This commit is contained in:
Oleksandr Klymenko
2025-07-11 22:36:29 +03:00
committed by GitHub
parent 2ccc15671f
commit 3e0fd11a96
2 changed files with 33 additions and 14 deletions
Download Patch File Download Diff File Expand all files Collapse all files

43
src/main/java/com/thealgorithms/strings/Isomorphic.java
View File

@@ -5,35 +5,54 @@ import java.util.HashSet;
import java.util.Map;
import java.util.Set;
/**
* Utility class to check if two strings are isomorphic.
*
* <p>
* Two strings {@code s} and {@code t} are isomorphic if the characters in {@code s}
* can be replaced to get {@code t}, while preserving the order of characters.
* Each character must map to exactly one character, and no two characters can map to the same character.
* </p>
*
* @see <a href="https://en.wikipedia.org/wiki/Isomorphism_(computer_science)">Isomorphic Strings</a>
*/
public final class Isomorphic {
private Isomorphic() {
}
public static boolean checkStrings(String s, String t) {
/**
* Checks if two strings are isomorphic.
*
* @param s the first input string
* @param t the second input string
* @return {@code true} if {@code s} and {@code t} are isomorphic; {@code false} otherwise
*/
public static boolean areIsomorphic(String s, String t) {
if (s.length() != t.length()) {
return false;
}
// To mark the characters of string using MAP
// character of first string as KEY and another as VALUE
// now check occurence by keeping the track with SET data structure
Map<Character, Character> characterMap = new HashMap<>();
Set<Character> trackUniqueCharacter = new HashSet<>();
Map<Character, Character> map = new HashMap<>();
Set<Character> usedCharacters = new HashSet<>();
for (int i = 0; i < s.length(); i++) {
if (characterMap.containsKey(s.charAt(i))) {
if (t.charAt(i) != characterMap.get(s.charAt(i))) {
char sourceChar = s.charAt(i);
char targetChar = t.charAt(i);
if (map.containsKey(sourceChar)) {
if (map.get(sourceChar) != targetChar) {
return false;
}
} else {
if (trackUniqueCharacter.contains(t.charAt(i))) {
if (usedCharacters.contains(targetChar)) {
return false;
}
characterMap.put(s.charAt(i), t.charAt(i));
map.put(sourceChar, targetChar);
usedCharacters.add(targetChar);
}
trackUniqueCharacter.add(t.charAt(i));
}
return true;
}
}