LeetCode Solutions

A collection of LeetCode problem solutions in Python and Java.

Problems Solved (48 Total)

Easy Problems

#	Problem	Difficulty
1	Two Sum	Easy
7	Reverse Integer	Easy
9	Palindrome Number	Easy
20	Valid Parentheses	Easy
26	Remove Duplicates from Sorted Array	Easy
27	Remove Element	Easy
66	Plus One	Easy
69	Sqrt(x)	Easy
82	Remove Duplicates from Sorted List	Easy
83	Remove Duplicates from Sorted List	Easy
88	Merge Sorted Array	Easy
125	Valid Palindrome	Easy
136	Single Number	Easy
167	Two Sum II - Input Array Is Sorted	Easy
202	Happy Number	Easy
232	Implement Queue using Stacks	Easy
258	Add Digits	Easy
268	Missing Number	Easy
283	Move Zeroes	Easy
344	Reverse String	Easy
345	Reverse Vowels of a String	Easy
349	Intersection of Two Arrays	Easy
350	Intersection of Two Arrays II	Easy
387	First Unique Character in a String	Easy
412	Fizz Buzz	Easy
509	Fibonacci Number	Easy
728	Self Dividing Numbers	Easy
933	Number of Recent Calls	Easy
1003	Verify an Alien Dictionary	Easy
1021	Remove Outermost Parentheses	Easy
1046	Last Stone Weight	Easy
1475	Final Prices With a Special Discount in a Shop	Easy
1544	Make The String Great	Easy
1700	Number of Students Unable to Eat Lunch	Easy
2073	Time Needed to Buy Tickets	Easy
2079	Watering Plants	Easy
2351	First Letter to Appear Twice	Easy
3174	Clear Digits	Easy

Medium Problems

#	Problem	Difficulty
11	Container With Most Water	Medium
15	3Sum	Medium
28	Find the Index of the First Occurrence in a String	Medium
35	Search Insert Position	Medium
71	Simplify Path	Medium
155	Min Stack	Medium
316	Remove Duplicate Letters	Medium
2015	Watering Plants II	Medium
2696	Minimum String Length After Removing Substrings	Medium

Solution Overview

Array Problems

• Two Sum (1) - Hash map approach
• Remove Duplicates (26) - Two-pointer technique
• Remove Element (27) - Two-pointer technique
• Merge Sorted Array (88) - Backward merge
• Move Zeroes (283) - Two-pointer swap
• Intersection of Two Arrays (349) - Set-based approach
• Add Digits (258) - Iterative digit sum
• Time Needed to Buy Tickets (2073) - Greedy simulation

String Problems

• Valid Parentheses (20) - Stack-based validation
• Valid Palindrome (125) - Alphanumeric filtering
• Reverse String (344) - Two-pointer swap
• Reverse Vowels (345) - Vowel filtering with two-pointers
• Find Index of First Occurrence (28) - Pattern matching
• Simplify Path (71) - Stack-based path parsing
• Make The String Great (1544) - Stack with case-insensitive comparison
• Minimum String Length (2696) - Stack-based substring removal
• Clear Digits (3174) - Stack with digit removal
• First Unique Character (387) - Hash map with index tracking
• First Letter to Appear Twice (2351) - Set-based occurrence tracking

Math Problems

• Reverse Integer (7) - Bit manipulation
• Palindrome Number (9) - String conversion
• Single Number (136) - XOR bitwise operation
• Missing Number (268) - XOR approach
• Fibonacci Number (509) - Dynamic array building
• Self Dividing Numbers (728) - Modulo validation
• Fizz Buzz (412) - Modulo conditions

Two-Pointer Problems

• 3Sum (15) - Sorted array with two-pointer
• Container With Most Water (11) - Greedy approach
• Two Sum II (167) - Two-pointer on sorted array
• Watering Plants (2079) - Greedy simulation
• Watering Plants II (2015) - Bidirectional greedy

Stack Problems

• Valid Parentheses (20)
• Make The String Great (1544)
• Minimum String Length (2696)
• Clear Digits (3174)
• Number of Students (1700) - Queue simulation

Queue Problems

• Number of Recent Calls (933) - Deque-based sliding window

Binary Search

• Search Insert Position (35) - Java implementation

File Organization

• .py files: Python solutions (46)
• .java files: Java solutions (1)
• .sql files: SQL solutions (1)