LeetCode Algorithm # Title Solution Tags Difficulty 3 Longest Substring Without Repeating Characters c++-I String Medium 5 Longest Palindromic Substring c++-I,c++-II String Medium 6 ZigZag Conversion c++ String Medium 8 String to Integer (atoi) c++ String Medium 10 Regular Expression Matching c++ String Hard 12 Integer to Roman c++ String Medium 13 Roman to Integer c++ String Easy 14 Longest Common Prefix c++ String Easy 17 Letter Combinations of a Phone Number c++ String Medium 20 Valid Parentheses c++ String Easy 22 Generate Parentheses c++ String Medium 28 Implement strStr() c++ String Easy 30 Substring with Concatenation of All Words c++ String Hard 32 Longest Valid Parentheses c++ String Hard 38 Count and Say c++ String Easy 43 Multiply Strings c++ String Medium 44 Wildcard Matching* c++ String Hard 49 Group Anagrams c++ String Medium 56 Merge Intervals c++,py Sort Medium 57 Insert Interval c++ Sort Hard 58 Length of Last Word c++ String Easy 65 Valid Number c++ String Hard 67 Add Binary c++ String Easy 68 Text Justification c++ String Hard 71 Simplify Path c++ String Medium 72 Edit Distance c++-I,c++-II String Hard 75 Sort Colors c++ Sort Medium 76 Minimum Window Substring c++ String Hard 87 Scramble String c++ String Hard 91 Decode Ways c++ String Medium 93 Restore IP Addresses c++ String Medium 97 Interleaving String c++ String Hard 115 Distinct Subsequences c++ String Hard 125 Valid Palindrome c++ String Easy 126 Word Ladder II c++ String Hard 147 Insertion Sort List c++ Sort Medium 148 Sort List c++ Sort Medium 151 Reverse Words in a String c++ String Medium 164 Maximum Gap c++ Sort Hard 165 Compare Version Numbers c++ String Medium 179 Largest Number c++ Sort Medium 242 Valid Anagram c++-I,c++-II Sort Easy 274 H-Index c++-I,c++-II Sort Medium 324 Wiggle Sort II c++-I,c++-II Sort Medium 349 Intersection of Two Arrays c++ Sort Easy 350 Intersection of Two Arrays II c++ Sort Easy 524 Longest Word in Dictionary through Deleting c++ Sort Medium