Coding Challenge 1: Palindrome Check
Write a Java program to check if a given string is a palindrome.
Solution:
import java.util.Scanner;
public class PalindromeCheck {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.print("Enter a string: ");
String input = scanner.nextLine();
if (isPalindrome(input)) {
System.out.println("The string is a palindrome.");
} else {
System.out.println("The string is not a palindrome.");
}
}
private static boolean isPalindrome(String str) {
String reversed = new StringBuilder(str).reverse().toString();
return str.equals(reversed);
}
}
Coding Challenge 2: Fibonacci Series
Problem: Write a Java program to print the Fibonacci series up to a given number of terms.
Solution:
import java.util.Scanner;
public class FibonacciSeries {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.print("Enter the number of terms in the Fibonacci series: ");
int n = scanner.nextInt();
printFibonacciSeries(n);
}
private static void printFibonacciSeries(int n) {
int a = 0, b = 1;
System.out.println("Fibonacci Series:");
for (int i = 0; i < n; i++) {
System.out.print(a + " ");
int temp = a;
a = b;
b = temp + b;
}
}
}
Coding Challenge 3: Prime Number Check
Problem: Write a Java program to check if a given number is prime.
Solution:
import java.util.Scanner;
public class PrimeNumberCheck {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.print("Enter a number: ");
int number = scanner.nextInt();
if (isPrime(number)) {
System.out.println(number + " is a prime number.");
} else {
System.out.println(number + " is not a prime number.");
}
}
private static boolean isPrime(int num) {
if (num <= 1) {
return false;
}
for (int i = 2; i <= Math.sqrt(num); i++) {
if (num % i == 0) {
return false;
}
}
return true;
}
}
Reverse a String
Problem: Write a Java program to reverse a given string without using any built-in functions or libraries.
Solution:
public class ReverseString {
public static void main(String[] args) {
String original = "Hello, World!";
String reversed = reverseString(original);
System.out.println("Original: " + original);
System.out.println("Reversed: " + reversed);
}
private static String reverseString(String str) {
char[] chars = str.toCharArray();
int left = 0;
int right = chars.length - 1;
while (left < right) {
char temp = chars[left];
chars[left] = chars[right];
chars[right] = temp;
left++;
right--;
}
return new String(chars);
}
}
Find the First Non-Repeated Character
Problem: Write a Java program to find the first non-repeated character in a string.
Solution:
public class FirstNonRepeatedChar {
public static void main(String[] args) {
String input = "programming";
char result = findFirstNonRepeatedChar(input);
System.out.println("First non-repeated character: " + result);
}
private static char findFirstNonRepeatedChar(String str) {
int[] charCount = new int[256];
for (char ch : str.toCharArray()) {
charCount[ch]++;
}
for (char ch : str.toCharArray()) {
if (charCount[ch] == 1) {
return ch;
}
}
return '\0'; // Return null character if no non-repeated character is found
}
}
You can try as below for practice.
1. Reverse a String
Write a Java program to reverse a given string without using any built-in functions or libraries.
2. Check for Palindrome
Write a Java program to check if a given string is a palindrome.
3. Find the First Non-Repeated Character
Write a Java program to find the first non-repeated character in a string.
4. Fibonacci Series
Write a Java program to generate the Fibonacci series up to a specified number of terms.
5. Factorial Calculation
Write a Java program to calculate the factorial of a given number.
6. Check for Prime Number
Write a Java program to check if a given number is prime.
7. Find the Missing Number
Write a Java program to find the missing number in an array of 1 to N.
8. Rotate an Array
Write a Java program to rotate elements in an array to the right by a specified number of positions.
9. Check for Anagrams
Write a Java program to check if two strings are anagrams of each other.
10. Implement a Stack
Write a Java program to implement a stack with push, pop, and peek operations.
11. Implement a Queue using Stacks
Write a Java program to implement a queue using two stacks.
12. Find the Maximum Subarray Sum
Write a Java program to find the maximum sum of a subarray in an array of integers.
13. Reverse a Linked List
Write a Java program to reverse a linked list.
14. Binary Search
Write a Java program to perform a binary search on a sorted array.
15. Implement a Binary Tree
Write a Java program to implement a binary tree with basic operations like insertion and traversal.
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