31/07/2024
common string-based data structure coding examples in Java that can be useful for interviews:
# # # 1. Reverse a String
```java
public class ReverseString {
public static void main(String[] args) {
String original = "JobSupport24";
String reversed = new StringBuilder(original).reverse().toString();
System.out.println("Reversed String: " + reversed);
}
}
```
# # # 2. Check if a String is a Palindrome
```java
public class PalindromeCheck {
public static void main(String[] args) {
String input = "racecar";
boolean isPalindrome = isPalindrome(input);
System.out.println("Is Palindrome: " + isPalindrome);
}
public static boolean isPalindrome(String s) {
int left = 0, right = s.length() - 1;
while (left < right) {
if (s.charAt(left) != s.charAt(right)) {
return false;
}
left++;
right--;
}
return true;
}
}
```
# # # 3. Find the First Non-Repeated Character
```java
import java.util.LinkedHashMap;
import java.util.Map;
public class FirstNonRepeatedChar {
public static void main(String[] args) {
String input = "swiss";
char firstNonRepeated = firstNonRepeatedCharacter(input);
System.out.println("First Non-Repeated Character: " + firstNonRepeated);
}
public static char firstNonRepeatedCharacter(String s) {
Map charCount = new LinkedHashMap();
for (char c : s.toCharArray()) {
charCount.put(c, charCount.getOrDefault(c, 0) + 1);
}
for (Map.Entry entry : charCount.entrySet()) {
if (entry.getValue() == 1) {
return entry.getKey();
}
}
throw new RuntimeException("No non-repeated character found");
}
}
```
# # # 4. Longest Substring Without Repeating Characters
```java
import java.util.HashSet;
import java.util.Set;
public class LongestSubstringWithoutRepeating {
public static void main(String[] args) {
String input = "abcabcbb";
int length = lengthOfLongestSubstring(input);
System.out.println("Length of Longest Substring Without Repeating Characters: " + length);
}
public static int lengthOfLongestSubstring(String s) {
Set set = new HashSet();
int maxLength = 0, left = 0, right = 0;
while (right < s.length()) {
if (!set.contains(s.charAt(right))) {
set.add(s.charAt(right));
right++;
maxLength = Math.max(maxLength, set.size());
} else {
set.remove(s.charAt(left));
left++;
}
}
return maxLength;
}
}
```
# # # 5. String Permutations
```java
public class StringPermutations {
public static void main(String[] args) {
String input = "ABC";
permute(input, 0, input.length() - 1);
}
public static void permute(String str, int l, int r) {
if (l == r) {
System.out.println(str);
} else {
for (int i = l; i
