I have curated these problems based on my experience of grinding leetcode. These were selected to cover wide range of sub-topics, and difficulties.
<h3 id="heading-easy-1010">Easy (10/10)</h3>
<ul>
<li><a target="_blank" href="https://leetcode.com/problems/valid-palindrome/">Valid Palindrome</a></li>
<li><a target="_blank" href="https://leetcode.com/problems/valid-palindrome-ii/">Valid Palindrome II</a></li>
<li><a target="_blank" href="https://leetcode.com/problems/longest-palindrome/">Longest Palindrome</a></li>
<li><a target="_blank" href="https://leetcode.com/problems/valid-parentheses/">Valid Parentheses</a></li>
<li><a target="_blank" href="https://leetcode.com/problems/count-binary-substrings/">Count Binary Substrings</a></li>
<li><a target="_blank" href="https://leetcode.com/problems/first-unique-character-in-a-string/">First Unique Character in a String</a></li>
<li><a target="_blank" href="https://leetcode.com/problems/valid-anagram/">Valid Anagram</a></li>
<li><a target="_blank" href="https://leetcode.com/problems/longest-common-prefix/">Longest Common Prefix</a></li>
<li><a target="_blank" href="https://leetcode.com/problems/is-subsequence/">Is Subsequence</a></li>
<li><a target="_blank" href="https://leetcode.com/problems/shuffle-string/">Shuffle String</a>
<h3 id="heading-medium-1717">Medium (17/17)</h3>
</li>
<li><a target="_blank" href="https://leetcode.com/problems/sort-characters-by-frequency/">Sort Characters By Frequency</a>
</li>
<li><a target="_blank" href="https://leetcode.com/problems/longest-common-subsequence/">Longest Common Subsequence</a></li>
<li><a target="_blank" href="https://leetcode.com/problems/longest-palindromic-subsequence/">Longest Palindromic Subsequence</a></li>
<li><a target="_blank" href="https://leetcode.com/problems/longest-string-chain/">Longest String Chain</a> #Hashtable #TwoPointers #String #DynamicProgramming #Array</li>
<li><a target="_blank" href="https://leetcode.com/problems/longest-substring-without-repeating-characters/">Longest Substring Without Repeating Characters</a></li>
<li><a target="_blank" href="https://leetcode.com/problems/find-all-anagrams-in-a-string/">Find All Anagrams in a String</a></li>
<li><a target="_blank" href="https://leetcode.com/problems/letter-combinations-of-a-phone-number/">Letter Combinations of a Phone Number</a></li>
<li><a target="_blank" href="https://leetcode.com/problems/top-k-frequent-words/">Top K Frequent Words</a></li>
<li><a target="_blank" href="https://leetcode.com/problems/generate-parentheses/">Generate Parentheses</a></li>
<li><a target="_blank" href="https://leetcode.com/problems/permutation-in-string/">Permutation in String</a></li>
<li><a target="_blank" href="https://leetcode.com/problems/palindromic-substrings/">Palindromic Substrings</a></li>
<li><a target="_blank" href="https://leetcode.com/problems/palindrome-partitioning/">Palindrome Partitioning</a> #Backtracking #DynamicProgramming #String</li>
<li><a target="_blank" href="https://leetcode.com/problems/reverse-substrings-between-each-pair-of-parentheses/">Reverse Substrings Between Each Pair of Parentheses</a></li>
<li><a target="_blank" href="https://leetcode.com/problems/longest-happy-string/">Longest Happy String</a></li>
<li><a target="_blank" href="https://leetcode.com/problems/word-break/">Word Break</a></li>
<li><a target="_blank" href="https://leetcode.com/problems/interleaving-string/">Interleaving String</a></li>
<li><a target="_blank" href="https://leetcode.com/problems/word-search/">Word Search</a></li>
</ul>
<h3 id="heading-hard-88">Hard (8/8)</h3>
<ul>
<li><a target="_blank" href="https://leetcode.com/problems/minimum-window-substring/">Minimum Window Substring</a></li>
<li><a target="_blank" href="https://leetcode.com/problems/word-search-ii/">Word Search II</a></li>
<li><a target="_blank" href="https://leetcode.com/problems/palindrome-partitioning-ii/">Palindrome Partitioning II</a></li>
<li><a target="_blank" href="https://leetcode.com/problems/longest-valid-parentheses/">Longest Valid Parentheses</a></li>
<li><a target="_blank" href="https://leetcode.com/problems/distinct-subsequences/">Distinct Subsequences</a></li>
<li><a target="_blank" href="https://leetcode.com/problems/distinct-subsequences-ii/">Distinct Subsequences II</a></li>
<li><a target="_blank" href="https://leetcode.com/problems/minimum-insertion-steps-to-make-a-string-palindrome/">Minimum Insertion Steps to Make a String Palindrome</a></li>
<li><a target="_blank" href="https://leetcode.com/problems/count-different-palindromic-subsequences/">Count Different Palindromic Subsequences</a> </li>
</ul>

I have curated these problems based on my experience of grinding leetcode. These were selected to cover wide range of sub-topics, and difficulties.

### Easy (10/10)

- [Valid Palindrome](https://leetcode.com/problems/valid-palindrome/)
-  **[Valid Palindrome II](https://leetcode.com/problems/valid-palindrome-ii/)**
-  [Longest Palindrome](https://leetcode.com/problems/longest-palindrome/)
-  [Valid Parentheses](https://leetcode.com/problems/valid-parentheses/)
-   **[Count Binary Substrings](https://leetcode.com/problems/count-binary-substrings/)**
-   **[First Unique Character in a String](https://leetcode.com/problems/first-unique-character-in-a-string/)**
-   **[Valid Anagram](https://leetcode.com/problems/valid-anagram/)**
-   **[Longest Common Prefix](https://leetcode.com/problems/longest-common-prefix/)**
-   **[Is Subsequence](https://leetcode.com/problems/is-subsequence/)**
-   **[Shuffle String](https://leetcode.com/problems/shuffle-string/)**
### Medium (17/17)

-   **[Sort Characters By Frequency](https://leetcode.com/problems/sort-characters-by-frequency/)**
-   [**Longest Common Subsequence**](https://leetcode.com/problems/longest-common-subsequence/)
-   [**Longest Palindromic Subsequence**](https://leetcode.com/problems/longest-palindromic-subsequence/)
-   **[Longest String Chain](https://leetcode.com/problems/longest-string-chain/)** #Hashtable #TwoPointers #String #DynamicProgramming #Array
-    [Longest Substring Without Repeating Characters](https://leetcode.com/problems/longest-substring-without-repeating-characters/)
-   **[Find All Anagrams in a String](https://leetcode.com/problems/find-all-anagrams-in-a-string/)**
-   **[Letter Combinations of a Phone Number](https://leetcode.com/problems/letter-combinations-of-a-phone-number/)**
-   **[Top K Frequent Words](https://leetcode.com/problems/top-k-frequent-words/)**
-   **[Generate Parentheses](https://leetcode.com/problems/generate-parentheses/)**
-   **[Permutation in String](https://leetcode.com/problems/permutation-in-string/)**
-   **[Palindromic Substrings](https://leetcode.com/problems/palindromic-substrings/)**
-   **[Palindrome Partitioning](https://leetcode.com/problems/palindrome-partitioning/)** #Backtracking #DynamicProgramming #String
-   **[Reverse Substrings Between Each Pair of Parentheses](https://leetcode.com/problems/reverse-substrings-between-each-pair-of-parentheses/)**
-   **[Longest Happy String](https://leetcode.com/problems/longest-happy-string/)**
-   **[Word Break](https://leetcode.com/problems/word-break/)**
-   **[Interleaving String](https://leetcode.com/problems/interleaving-string/)**
-   **[Word Search](https://leetcode.com/problems/word-search/)**

### Hard (8/8)

-   **[Minimum Window Substring](https://leetcode.com/problems/minimum-window-substring/)**
-   **[Word Search II](https://leetcode.com/problems/word-search-ii/)**
-   **[Palindrome Partitioning II](https://leetcode.com/problems/palindrome-partitioning-ii/)**
-   **[Longest Valid Parentheses](https://leetcode.com/problems/longest-valid-parentheses/)**
-   **[Distinct Subsequences](https://leetcode.com/problems/distinct-subsequences/)**
-   **[Distinct Subsequences II](https://leetcode.com/problems/distinct-subsequences-ii/)**
-   **[Minimum Insertion Steps to Make a String Palindrome](https://leetcode.com/problems/minimum-insertion-steps-to-make-a-string-palindrome/)**
-   **[Count Different Palindromic Subsequences](https://leetcode.com/problems/count-different-palindromic-subsequences/)** 




Curated Series: String Problems

Easy (10/10)

Medium (17/17)

Hard (8/8)

All about my learnings in the CS & Software Engineering World. Currently, sharing my solutions to popular coding questions with occasional notes on System Design.


All about my learnings in the CS &amp; Software Engineering World. Currently, sharing my solutions to popular coding questions with occasional notes on System Design.


Curated Series: String Problems

Table of contents

Easy (10/10)

Medium (17/17)

Hard (8/8)