ASM - CoreJava Strings - 1

 

String Assignments - 1

 

1.       Reverse a String: Write a Java program to reverse a given string.

Algorithm:

·         Initialize an empty string to store the reversed result.

·         Traverse the input string from end to start and append each character to the result string.

 

2.       Count Vowels and Consonants: Write a Java program to count the number of vowels and consonants in a given string.

Algorithm:

·         Initialize counters for vowels and consonants to zero.

·         Iterate through each character in the string.

·         Check if the character is a vowel (a, e, i, o, u) and increment the vowel count, otherwise increment the consonant count.

3.       Check for Palindrome: Write a Java program to check if a given string is a palindrome.

Algorithm:

·         Remove spaces and convert the string to lowercase.

·         Compare the original string with its reverse to check if it's a palindrome.

4.       Count Words in a Sentence: Write a Java program to count the number of words in a given sentence.

Algorithm:

·         Split the input sentence into words using whitespace as a delimiter.

·         Count the number of words in the resulting array.

5.       Concatenate Strings: Write a Java program to concatenate two strings without using the + operator.

Algorithm:

·         Use a StringBuilder or StringBuffer to append the second string to the first.

6.       Remove Duplicates from a String: Write a Java program to remove duplicate characters from a string.

·         Algorithm:

·         Use a Set to keep track of unique characters while iterating through the string.

Check for Anagrams: Write a Java program to check if two strings are anagrams.

Algorithm:

·         Remove spaces and convert both strings to lowercase.

·         Sort the characters in both strings and compare them.

7.       Find the Most Common Character: Write a Java program to find the most common character in a string.

Algorithm:

·         Use a HashMap to store character frequencies and find the character with the highest frequency.

8.       Reverse Words in a Sentence: Write a Java program to reverse the words in a given sentence.

Algorithm:

·         Split the sentence into words and reverse their order.

9.       Count Occurrences of a Substring: Write a Java program to count the occurrences of a substring in a given string.

Algorithm:

·         Use the indexOf method in a loop to find all occurrences of the substring.

10.   Check for Rotation: Write a Java program to check if one string is a rotation of another.

Algorithm:

·         Concatenate the first string with itself and check if the second string is a substring of the result.

11.   String Compression: Write a Java program to compress a string by replacing repeated characters with a count.

Algorithm:

·         Iterate through the string, counting consecutive characters and appending the count to the result.

12.   String to Integer Conversion: Write a Java program to convert a string containing an integer to an actual integer.

Algorithm:

·         Iterate through the characters, converting them to integers and accumulating the result.

13.   Remove Specific Characters: Write a Java program to remove all occurrences of a specific character from a string.

Algorithm:

Use a StringBuilder or StringBuffer to build the result string, excluding the specified character.

14.   Generate Random Password: Write a Java program to generate a random password of a specified length.

Algorithm:

·         Create a pool of characters (letters, digits, symbols) and randomly select characters for the password.

15.   Check for Subsequence: Write a Java program to check if one string is a subsequence of another.

Algorithm:

·         Use two pointers to traverse both strings and check if the characters match.

16.   String Permutations: Write a Java program to generate all permutations of a given string.

Algorithm:

·         Use a recursive approach to generate permutations by swapping characters.

17.   String Splitting: Write a Java program to split a string into multiple lines with a maximum line length.

Algorithm:

·         Iterate through the string, splitting it into lines not exceeding the maximum length.

18.   Character Frequency Count: Write a Java program to count the frequency of each character in a string and display the results.

Algorithm:

·         Use a HashMap to store character frequencies and display the results.

19.   Remove Extra Spaces: Write a Java program to remove extra spaces from a string.

Algorithm:

·         Replace multiple consecutive spaces with a single space using regular expressions.

20.   CamelCase to Underscore: Write a Java program to convert a CamelCase string to an underscore-separated string.

Algorithm:

Iterate through the string and insert underscores before uppercase letters.

21.   String Encryption: Write a Java program to encrypt a string using a simple substitution cipher.

Algorithm:

·         Define a mapping from each character to another character and replace characters accordingly.

22.   String Matching: Write a Java program to find all occurrences of a pattern in a given text.

Algorithm:

·         Use a loop and the indexOf method to find all occurrences of the pattern.

23.   String Rotation Detection: Write a Java program to detect if one string is a rotation of another using the contains method.

Algorithm:

·         Concatenate the first string with itself and check if it contains the second string.

24.   String Comparison with Wildcard: Write a Java program to compare two strings with wildcard characters (* and ?).

Algorithm:

·         Implement a custom pattern matching algorithm that handles wildcard characters.

25.   Shuffle Characters in a String: Write a Java program to randomly shuffle the characters in a given string.

Algorithm:

·         Convert the string to a character array and use a random number generator to shuffle the characters.

26.   Common Characters in Two Strings: Write a Java program to find the common characters between two strings.

Algorithm:

·         Use two arrays to count the frequency of characters in each string and find common characters.

27.   Find Anagram Groups in a List of Strings: Write a Java program to group anagrams from a list of strings.

Algorithm:

·         Use a HashMap where the key is a sorted version of a word, and the value is a list of anagrams.

28.   Find All Palindromic Substrings: Write a Java program to find all palindromic substrings within a given string.

Algorithm:

·         Use dynamic programming or expand around the centre to identify all palindromic substrings.

29.   Reverse Words in a Sentence with an Array: Write a Java program to reverse the words in a given sentence while preserving the word order using arrays.

Algorithm:

·         Split the sentence into words and store them in an array.

·         Reverse the array containing the words.

·         Reconstruct the sentence by joining the reversed words with spaces.

30.   Count Substrings with Exactly K Distinct Characters: Write a Java program to count the number of substrings in a string with exactly K distinct characters.

Algorithm:

·         Use a sliding window approach to count substrings with exactly K distinct characters.

31.   Longest Common Prefix of Multiple Strings: Write a Java program to find the longest common prefix among an array of strings.

Algorithm:

·         Find the shortest string in the array.

·         Compare each character of the shortest string with the other strings in the array.

32.   Compress String Using Array: Write a Java program to compress a string by replacing repeated characters with a count using arrays.

Algorithm:

·         Iterate through the string, using an array to count consecutive characters.

·         Append the character and its count to the result string.

33.   Largest Common Substring: Write a Java program to find the largest common substring in an array of strings.

Algorithm:

·         Compare each string with the others to find the largest common substring.

34.   Find the Longest Word Formed by Other Words: Write a Java program to find the longest word in an array of words that can be formed by concatenating other words in the array.

Algorithm:

·         Sort the array of words by length.

·         Check if each word can be formed using shorter words in the array.

 

35.   Longest Substring Without Repeating Characters: Write a Java program to find the length of the longest substring without repeating characters in a given string.

Algorithm:

1.       Initialize variables start and maxLen to 0.

2.       Create a HashSet to store unique characters.

3.       Iterate through the string with a pointer end.

4.       If the character at end is not in the HashSet, add it and update maxLen as maxLen = max(maxLen, end - start + 1).

5.       If the character at end is in the HashSet, remove characters from the start of the substring until the repeated character is removed.

6.       Increment start pointer to continue searching for a longer substring.

7.       Repeat steps 3-6 until end reaches the end of the string.

36.   String Parsing: Write a Java program to parse a string containing key-value pairs (e.g., "name=John age=30").

Algorithm:

1.       Split the input string by spaces to obtain an array of key-value pairs.

2.       Create a HashMap to store the parsed key-value pairs.

3.       Iterate through the array of pairs.

4.       Split each pair by the '=' sign to separate the key and value.

5.       Store the key and value in the HashMap.

37.   String to Morse Code Conversion: Write a Java program to convert a string to Morse code.

Algorithm:

1.       Create a mapping of characters to their Morse code representations.

2.       Initialize an empty string to store the Morse code result.

3.       Iterate through each character in the input string.

4.       Convert the character to its Morse code representation using the mapping.

5.       Append the Morse code representation to the result string.

38.   String Matching with Regular Expressions: Write a Java program to match a string against a regular expression pattern.

Algorithm:

1.       Create a regular expression pattern using the Pattern.compile method.

2.       Create a Matcher object by applying the pattern to the input string.

3.       Use the find method of the Matcher to search for matches.

4.       Retrieve and work with the matched substrings as needed.

39.   String Truncation: Write a Java program to truncate a string to a specified maximum length, adding ellipses if necessary.

Algorithm:

1.       Check if the length of the input string is less than or equal to the specified maximum length.

2.       If the string is within the length limit, no truncation is needed.

3.       If the string is longer, truncate it to the maximum length.

4.       Add ellipses ("...") to the truncated string to indicate truncation.

40.   String Encryption with Key: Write a Java program to encrypt a string using a provided encryption key.

Algorithm:

1.       Define an encryption algorithm that takes the input string and the encryption key.

2.       Apply the encryption algorithm to transform the input string using the provided key.

3.       Return the encrypted string as the result.

41.   String Comparison with Levenshtein Distance: Write a Java program to compare two strings based on their Levenshtein distance (edit distance).

Algorithm:

1.       Implement the Levenshtein distance algorithm to calculate the minimum number of edits (insertions, deletions, substitutions) needed to transform one string into another.

2.       Compare the Levenshtein distance between the two strings to determine their similarity.

42.   String Pattern Matching Using Wildcards: Write a Java program to match a string against a pattern that includes wildcards (* and ?).

Algorithm:

1.       Implement a custom pattern matching algorithm that handles wildcards (*) and (?).

2.       Iterate through the pattern and input string to match characters and wildcards as needed.

3.       Return the result of the pattern match.

43.   String Case Conversion: Write a Java program to convert a string to uppercase and lowercase.

·         Algorithm:

1.       Use the toUpperCase method to convert the string to uppercase.

2.       Use the toLowerCase method to convert the string to lowercase.

44.   String to Hexadecimal Conversion: Write a Java program to convert a string to its hexadecimal representation.

Algorithm:

1.       Iterate through each character in the input string.

2.       Convert each character to its hexadecimal representation using the Integer.toHexString method.

3.       Append the hexadecimal representation to the result string.