String Interview Questions | Practice Problems

A string is traditionally a sequence of characters, either as a literal constant or as some kind of variable. The latter may allow its elements to be mutated and the length changed, or it may be fixed (after creation).

A string is generally understood as a data type and is often implemented as an array of bytes (or words) that stores a sequence of elements, typically characters. String datatypes have historically allocated one byte per character. In C, the length of a string can be stored implicitly by using a special terminating character; often this is the null character (NUL), which has all bits zero.

Below is the list of commonly asked string interview questions –

  1. Check if given string is a rotated palindrome or not
  2. Longest Palindromic Substring (Non-DP Space Optimized Solution)
  3. Check if repeated subsequence is present in the string or not
  4. Check if strings can be derived from each other by circularly rotating them
  5. Check if given set of moves is circular or not
  6. Convert given number into corresponding excel column name
  7. Determine if two strings are anagram or not
  8. Find all binary strings that can be formed from given wildcard pattern
  9. Find all interleavings of given strings
  10. Isomorphic Strings
  11. Find all possible palindromic substrings in a string
  12. Find all possible combinations of words formed from mobile keypad
  13. Find all possible combinations by replacing given digits with characters of the corresponding list
  14. Find all words from given list that follows same order of characters as given pattern
  15. Find first k non-repeating characters in a string in single traversal
  16. Group anagrams together from given list of words
  17. Introduction to Pattern Matching
  18. Inplace remove all occurrences of ‘AB’ and ‘C’ from the string
  19. Longest even length palidromic sum substring
  20. Print string in zig-zag form in k rows
  21. Reverse given text without reversing the individual words
  22. Run Length Encoding (RLE) data compression algorithm
  23. Validate an IP address
  24. Find the longest substring of given string containing k distinct characters
  25. Find all palindromic permutations of a string
  26. Find all substrings of a string that are permutation of a given string
  27. Find the longest substring of given string containing all distinct characters
  28. Find all Permutations of a given string
  29. Iterative Approach to find Permutations of a String in C++ and Java
  30. Find all lexicographically next permutations of a string sorted in ascending order
  31. Generate all Permutations of a String in Java | Recursive & Iterative
  32. Find all Lexicographic Permutations of a String
  33. Find Lexicographically minimal string rotation
  34. Find all strings of given length containing balanced parentheses
  35. Find all N-digit binary numbers with k-bits set where k ranges from 1 to N
  36. Generate binary numbers between 1 to N
  37. Find all combinations of non-overlapping substrings of a string
  38. Find all N-digit binary numbers having more 1’s than 0’s for any prefix
  39. Find all N-digit numbers with given sum of digits
  40. Find all N-digit strictly increasing numbers (Bottom-Up and Top-Down Approach)
  41. Calculate rank of given string among all its lexicographically sorted permutations
  42. Combinations of words formed by replacing given numbers with corresponding alphabets
  43. Check if given sentence is syntactically correct or not
  44. Word Break Problem
  45. Wildcard Pattern Matching
  46. Count number of times a pattern appears in given string as a subsequence
  47. The Levenshtein distance (Edit distance) problem
  48. Longest Common Subsequence | Introduction & LCS Length
  49. Longest Common Subsequence | Space optimized version
  50. Longest Common Subsequence of K-sequences
  51. Longest Common Subsequence | Finding all LCS
  52. Longest Repeated Subsequence problem
  53. Longest Palindromic Subsequence using Dynamic Programming
  54. Find minimum cuts needed for palindromic partition of a string
  55. Longest Common Substring problem
  56. Shortest Common Supersequence | Introduction & SCS Length
  57. Shortest Common Supersequence | Finding all SCS
  58. Shortest Common Supersequence | Using LCS
  59. Implement Diff Utility
  60. Find all N-digit binary numbers with equal sum of bits in its two halves
  61. Check if given string is interleaving of two other given strings
  62. Difference between Subarray, Subsequence and Subset
  63. std::next_permutation | Overview & Implementation in C++
  64. std::prev_permutation | Overview & Implementation in C++
  65. Implementation of KMP Algorithm in C, C++ and Java
  66. Reverse String without using Recursion
  67. Reverse given string using Recursion
  68. Reverse a String in Java in 10 different ways
  69. Determine if a given string is palindrome or not


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