Python

This repo documents my solutions to Leetcode - programming questions, whose categories are described in the following. I wrote my solutions in Python, presented in Jupyter Notebook Leetcode Programming Questions.

Leetcode Problem Categories

1. String
2. Array
3. Matrix
4. Singly Linked List
5. Hash Table
6. Two Pointers
7. String Matching
8. Stack
9. Binary Tree
10. Greedy
11. Recursion
12. Math

1: String

Index	Question ID	Question title	Difficulty level
1	1108	Defanging an IP Address	Easy
2	2011	Final Value of Variable After Performing Operations	Easy
3	771	Jewels and Stones	Easy
4	2114	Maximum Number of Words Found in Sentences	Easy
5	1678	Goal Parser Interpretation	Easy
6	1221	Split a String in Balanced Strings	Easy
7	1528	Shuffle String	Easy
8	1773	Count Items Matching a Rule	Easy
9	2194	Cells in a Range on an Excel Sheet	Easy
10	2325	Decode the Message	Easy
11	1859	Sorting the Sentence	Easy
12	1662	Check If Two String Arrays are Equivalent	Easy
13	1832	Check if the Sentence Is Pangram	Easy
14	1816	Truncate Sentence	Easy
15	1768	Merge Strings Alternately	Easy
16	804	Unique Morse Code Words	Easy
17	709	To Lower Case	Easy
18	1684	Count the Number of Consistent Strings	Easy
19	1614	Maximum Nesting Depth of the Parentheses	Easy
20	2315	Count Asterisks	Easy
21	557	Reverse Words in a String III	Easy
22	2103	Rings and Rods	Easy
23	2697	Lexicographically Smallest Palindrome	Easy
24	1021	Remove Outermost Parentheses	Easy
25	1309	Decrypt String from Alphabet to Integer Mapping	Easy
26	2000	Reverse Prefix of Word	Easy
27	2678	Number of Senior Citizens	Easy
28	1704	Determine if String Halves Are Alike	Easy
29	1812	Determine Color of a Chessboard Square	Easy
30	942	DI String Match	Easy
31	2185	Counting Words With a Given Prefix	Easy
32	344	Reverse String	Easy
33	2586	Count the Number of Vowel Strings in Range	Easy
34	1332	Remove Palindromic Subsequences	Easy
35	657	Robot Return to Origin	Easy
36	944	Delete Columns to Make Sorted	Easy
37	2351	First Letter to Appear Twice	Easy
38	2278	Percentage of Letter in String	Easy
39	1880	Check if Word Equals Summation of Two Words	Easy
40	1974	Minimum Time to Type Word Using Special Typewriter	Easy
41	2255	Count Prefixes of a Given String	Easy
42	2053	Kth Distinct String in an Array	Easy
43	2496	Maximum Value of a String in an Array	Easy
44	1876	Substrings of Size Three with Distinct Characters	Easy
45	821	Shortest Distance to a Character	Easy
46	2399	Check Distances Between Same Letters	Easy
47	412	Fizz Buzz	Easy
48	2506	Count Pairs Of Similar Strings	Easy
49	2085	Count Common Words With One Occurrence	Easy
50	500	Keyboard Row	Easy
51	2309	Greatest English Letter in Upper and Lower Case	Easy
52	1160	Find Words That Can Be Formed by Characters	Easy
53	929	Unique Email Addresses	Easy
54	806	Number of Lines To Write String	Easy
55	2243	Calculate Digit Sum of a String	Easy
56	2138	Divide a String Into Groups of Size k	Easy
57	2224	Minimum Number of Operations to Convert Time	Easy
58	1598	Crawler Log Folder	Easy
59	1455	Check If a Word Occurs As a Prefix of Any Word in a Sentence	Easy
60	2068	Check Whether Two Strings are Almost Equivalent	Easy
61	2490	Circular Sentence	Easy
62	2710	Remove Trailing Zeros From a String	Easy
63	1078	Occurrences After Bigram	Easy
64	1507	Reformat Date	Easy
65	383	Ransom Note	Easy
66	389	Find the Difference	Easy
67	2264	Largest 3-Same-Digit Number in String	Easy
68	2451	Odd String Difference	Easy
69	748	Shortest Completing Word	Easy
70	2129	Capitalize the Title	Easy
71	599	Minimum Index Sum of Two Lists	Easy
72	819	Most Common Word	Easy
73	1689	Partitioning Into Minimum Number Of Deci-Binary Numbers	Medium
74	535	Encode and Decode TinyURL	Medium
75	1769	Minimum Number of Operations to Move All Balls to Each Box	Medium
76	2391	Minimum Amount of Time to Collect Garbage	Medium
77	2120	Execution of All Suffix Instructions Staying in a Grid	Medium
78	2125	Number of Laser Beams in a Bank	Medium
79	434	Number of Segments in a String	Easy
80	1805	Number of Different Integers in a String	Easy
81	2062	Count Vowel Substrings of a String	Easy
82	917	Reverse Only Letters	Easy
83	171	Excel Sheet Column Number	Easy
84	1945	Sum of Digits of String After Convert	Easy
85	1763	Longest Nice Substring	Easy
86	541	Reverse String II	Easy
87	1119	Remove Vowels from a String	Easy
88	2744	Find Maximum Number of String Pairs	Easy
89	760	Find Anagram Mappings	Easy
90	1213	Intersection of Three Sorted Arrays	Easy
91	1725	Number Of Rectangles That Can Form The Largest Square	Easy
92	1796	Second Largest Digit in a String	Easy
93	2716	Minimize String Length	Easy
94	2828	Check if a String Is an Acronym of Words	Easy
95	2810	Faulty Keyboard	Easy
96	1370	Increasing Decreasing String	Easy
97	2788	Split Strings by Separator	Easy
98	2696	Minimum String Length After Removing Substrings	Easy
99	1065	Index Pairs of a String	Easy

2. Array

Index	Question ID	Question title	Difficulty level
1	1920	Build Array from Permutation	Easy
2	1929	Concatenation of Array	Easy
3	1470	Shuffle the Array	Easy
4	1512	Number of Good Pairs	Easy
5	2574	Left and Right Sum Differences	Easy
6	2656	Maximum Sum With Exactly K Elements	Easy
7	2652	Sum Multiples	Easy
8	1913	Maximum Product Difference Between Two Pairs	Easy
9	561	Array Partition	Easy
10	1304	Find N Unique Integers Sum up to Zero	Easy
11	1464	Maximum Product of Two Elements in an Array	Easy
12	2500	Delete Greatest Value in Each Row	Easy
13	2176	Count Equal and Divisible Pairs in an Array	Easy
14	2553	Separate the Digits in an Array	Easy
15	2535	Difference Between Element Sum and Digit Sum of an Array	Easy
16	1588	Sum of All Odd Length Subarrays	Easy
17	1	Two Sum	Easy
18	2303	Calculate Amount Paid in Taxes	Easy
19	2078	Two Furthest Houses With Different Colors	Easy
20	575	Distribute Candies	Easy
21	2728	Count Houses in a Circular Street	Easy

3. Matrix

Index	Question ID	Question title	Difficulty level
1	1672	Richest Customer Wealth	Easy
2	2373	Largest Local Values in a Matrix	Easy
3	1351	Count Negative Numbers in a Sorted Matrix	Easy
4	2643	Row With Maximum Ones	Easy
5	1337	The K Weakest Rows in a Matrix	Easy
6	883	Projection Area of 3D Shapes	Easy
7	1380	Lucky Numbers in a Matrix	Easy
8	463	Island Perimeter	Easy
9	1030	Matrix Cells in Distance Order	Easy
10	766	Toeplitz Matrix	Easy
11	999	Available Captures for Rook	Easy
12	1260	Shift 2D Grid	Easy
13	2319	Check if Matrix Is X-Matrix	Easy
14	2639	Find the Width of Columns of a Grid	Easy
15	1582	Special Positions in a Binary Matrix	Easy
16	867	Transpose Matrix	Easy
17	892	Surface Area of 3D Shapes	Easy
18	1886	Determine Whether Matrix Can Be Obtained By Rotation	Easy
19	661	Image Smoother	Easy
20	1275	Find Winner on a Tic Tac Toe Game	Easy

4. Singly Linked List

Index	Question ID	Question title	Difficulty level
1	1290	Convert Binary Number in a Linked List to Integer	Easy
2	876	Middle of the Linked List	Easy
3	206	Reverse Linked List	Easy
4	2341	Maximum Number of Pairs in Array	Easy
5	705	Design HashSet	Easy
6	706	Design HashMap	Easy
7	21	Merge Two Sorted Lists	Easy
8	160	Intersection of Two Linked Lists	Easy
9	1474	Delete N Nodes After M Nodes of a Linked List	Easy

5. Hash Table

Index	Question ID	Question title	Difficulty level
1	2367	Number of Arithmetic Triplets	Easy
2	2215	Find the Difference of Two Arrays	Easy
3	1748	Sum of Unique Elements	Easy
4	961	N-Repeated Element in Size 2N Array	Easy
5	2341	Maximum Number of Pairs in Array	Easy
6	2363	Merge Similar Items	Easy
7	2032	Two Out of Three	Easy
8	2418	Sort the People	Easy
9	1436	Destination City	Easy
10	1941	Check if All Characters Have Equal Number of Occurrences	Easy
11	1742	Maximum Number of Balls in a Box	Easy
12	1935	Maximum Number of Words You Can Type	Easy
13	2006	Count Number of Pairs With Absolute Difference K	Easy
14	1365	How Many Numbers Are Smaller Than the Current Number	Easy
15	2670	Find the Distinct Difference Array	Easy
16	1207	Unique Number of Occurrences	Easy
17	2206	Divide Array Into Equal Pairs	Easy
18	2570	Merge Two 2D Arrays by Summing Values	Easy
19	1122	Relative Sort Array	Easy
20	387	First Unique Character in a String	Easy
21	1496	Path Crossing	Easy
22	290	Word Pattern	Easy
23	141	Linked List Cycle	Easy
24	2357	Make Array Zero by Subtracting Equal Amounts	Easy
25	1002	Find Common Characters	Easy
26	1394	Find Lucky Integer in an Array	Easy
27	1165	Single-Row Keyboard	Easy

6. Two Pointers

Easy Difficulty Questions

Index	Question ID	Question title	Difficulty level
1	832	Flipping an Image	Easy
2	905	Sort Array By Parity	Easy
3	977	Squares of a Sorted Array	Easy
4	349	Intersection of Two Arrays	Easy
5	922	Sort Array By Parity II	Easy
6	2562	Find the Array Concatenation Value	Easy
7	2441	Largest Positive Integer That Exists With Its Negative	Easy
8	1385	Find the Distance Value Between Two Arrays	Easy
9	283	Move Zeroes	Easy
10	2465	Number of Distinct Averages	Easy
11	202	Happy Number	Easy
12	2540	Minimum Common Value	Easy
13	345	Reverse Vowels of a String	Easy

7. String Matching

Index	Question ID	Question title	Difficulty level
1	1408	String Matching in an Array	Easy
2	796	Rotate String	Easy
3	459	Repeated Substring Pattern	Easy
4	28	Find the Index of the First Occurrence in a String	Easy
5	1668	Maximum Repeating Substring	Easy

8. Stack

Index	Question ID	Question title	Difficulty level
1	590	N-ary Tree Postorder Traversal	Easy
2	1475	Final Prices With a Special Discount in a Shop	Easy
3	682	Baseball Game	Easy
4	496	Next Greater Element I	Easy

9. Binary Tree

Index	Question ID	Question title	Difficulty level
1	938	Range Sum of BST	Easy
2	2236	Root Equals Sum of Children	Easy

10. Greedy

Index	Question ID	Question title	Difficulty level
1	1827	Minimum Operations to Make the Array Increasing	Easy
2	860	Lemonade Change	Easy
3	1903	Largest Odd Number in String	Easy
4	680	Valid Palindrome II	Easy
5	2591	Distribute Money to Maximum Children	Easy
6	2600	K Items With the Maximum Sum	Easy

11. Recursion

Index	Question ID	Question title	Difficulty level
1	509	Fibonacci Number	Easy
2	342	Power of Four	Easy
3	231	Power of Two	Easy
4	326	Power of Three	Easy
5	1265	Print Immutable Linked List in Reverse	Medium

12. Math

Index	Question ID	Question title	Difficulty level
1	2469	Convert the Temperature	Easy
2	2235	Add Two Integers	Easy
3	2413	Smallest Even Multiple	Easy
4	2769	Find the Maximum Achievable Number	Easy
5	2160	Minimum Sum of Four Digit Number After Splitting Digits	Easy
6	2520	Count the Digits That Divide a Number	Easy
7	2651	Calculate Delayed Arrival Time	Easy
8	1863	Sum of All Subset XOR Totals	Easy
9	2485	Find the Pivot Integer	Easy
10	1180	Count Substrings with Only One Distinct Letter	Easy
11	1266	Minimum Time Visiting All Points	Easy
12	2427	Number of Common Factors	Easy
13	1134	Armstrong Number	Easy
14	1252	Cells with Odd Values in a Matrix	Easy
15	1688	Count of Matches in Tournament	Easy
16	728	Self Dividing Numbers	Easy
17	1837	Sum of Digits in Base K	Easy
18	1085	Sum of Digits in the Minimum Number	Easy
19	2169	Count Operations to Obtain Zero	Easy
20	1217	Minimum Cost to Move Chips to The Same Position	Easy
21	2578	Split With Minimum Sum	Easy
22	2544	Alternating Digit Sum	Easy
23	762	Prime Number of Set Bits in Binary Representation	Easy
24	258	Add Digits	Easy
25	1025	Divisor Game	Easy
26	1925	Count Square Sum Triples	Easy
27	1716	Calculate Money in Leetcode Bank	Easy
28	268	Missing Number	Easy