Mastering Competitive Coding: String

Easy level questions

1. Word Break:

   • Input: s = "leetcode", wordDict = ["leet", "code"]
   • Output: True
   • Explanation: "leetcode" can be segmented into "leet" and "code".

2. Longest Palindromic Substring:

   • Input: s = "babad"
   • Output: "bab" or "aba"
   • Explanation: Both "bab" and "aba" are valid longest palindromic substrings.

3. Regular Expression Matching:

   • Input: s = "aa", p = "a*"
   • Output: True
   • Explanation: Pattern "a*" matches zero or more occurrences of 'a'.

4. Letter Combinations of a Phone Number:

   • Input: digits = "23"
   • Output: ["ad", "ae", "af", "bd", "be", "bf", "cd", "ce", "cf"]
   • Explanation: Corresponding letters for digits 2 and 3 are "abc" and "def" respectively.

5. Valid Palindrome II:

   • Input: s = "abca"
   • Output: True
   • Explanation: By deleting 'b', the resulting string "aca" is a palindrome.

6. Group Anagrams:

   • Input: strs = ["eat", "tea", "tan", "ate", "nat", "bat"]
   • Output: [["bat"], ["nat","tan"], ["ate","eat","tea"]]
   • Explanation: Anagrams are grouped together.

7. Minimum Window Substring:

   • Input: s = "ADOBECODEBANC", t = "ABC"
   • Output: "BANC"
   • Explanation: The minimum window substring containing all characters from t is "BANC".

8. Decode String:

   • Input: s = "3[a]2[bc]"
   • Output: "aaabcbc"
   • Explanation: Decode the string by repeating substrings inside brackets.

9. Permutations:

   • Input: nums = [1,2,3]
   • Output: [[1,2,3], [1,3,2], [2,1,3], [2,3,1], [3,1,2], [3,2,1]]
   • Explanation: All possible permutations of the input list.

10. Add Binary:

    • Input: a = "11", b = "1"
    • Output: "100"
    • Explanation: Binary addition of "11" and "1" results in "100".