LeetCode Solutions and Explanations

Here is a list of LeetCode problems solved by Goodtecher. Goodtecher will keep updating solutions and explains to LeetCode problems. You can also watch GoodTecher LeetCode Video Tutorial on Youtube.

LeetCode Problems Table

#TitleCategoryDifficultyFrequency
1Two SumTwo PointersEasy★★★★★
2Add Two NumbersLinked ListMedium★★★★
3Longest Substring Without Repeating CharactersTwo PointersMedium★★★★
4Median of Two Sorted ArraysArrayHard★★★
5Longest Palindromic SubstringDynamic ProgrammingMedium★★★★
6ZigZag ConversionMathMedium
7Reverse IntegerMathEasy★★★★
8String to Integer (atoi)StringMedium★★
9Palindrome NumberMathEasy★★★★
11Container With Most WaterTwo PointersMedium★★
12Integer to RomanStringMedium
13Roman to IntegerStringEasy
14Longest Common PrefixStringEasy★★★
153SumTwo PointersMedium★★★
163Sum ClosestTwo PointersMedium★★★
17Letter Combinations of a Phone NumberDepth First SearchMedium★★★
184SumTwo PointersMedium★★
19Remove Nth Node From End of ListLinked ListMedium★★★
20Valid ParenthesesStackEasy★★★★
21Merge Two Sorted ListsLinked ListEasy★★★
26Remove Duplicates from Sorted ArrayTwo PointersEasy★★
28Implement strStr()StringEasy★★
34Search for a RangeBinary SearchMedium★★
35Search Insert Position Binary SearchEasy★★
39Combination SumDepth First SearchMedium★★★★
40Combination Sum IIDepth First SearchMedium★★★
42Trapping Rain WaterTwo PointersHard★★★
62Unique PathsDynamic ProgrammingMedium★★★
63Unique Paths IIDynamic ProgrammingMedium★★
69Sqrt(x)Binary SearchEasy★★★
70Climbing StairsDynamic ProgrammingEasy★★★
78SubsetsDepth First SearchMedium★★★★
90Subsets IIDepth First SearchMedium★★
100Same TreeBinary TreeEasy★★★
101Symmetric TreeBinary TreeEasy★★★
102Binary Tree Level Order TraversalBinary TreeMedium★★★★
104Maximum Depth of Binary TreeBinary TreeEasy★★★
110Balanced Binary TreeBinary TreeEasy★★★
111Minimum Depth of Binary TreeBinary TreeEasy★★★
121Best Time to Buy and Sell StockArrayEasy★★
122Best Time to Buy and Sell Stock IIArrayEasy★★
138Copy List with Random PointerLinked ListMedium★★
139Word BreakDynamic ProgrammingMedium★★★★
144Binary Tree Preorder TraversalBinary TreeEasy★★
155Min StackStackEasy★★★
278First Bad VersionBinary SearchEasy★★
412Fizz BuzzMathEasy★★★
547Friend CirclesUnion FindMedium★★★

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