🧩 LeetCode Solutions in Java

Sharpening problem-solving skills one problem at a time!

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Live LeetCode Stats

LeetCode Topics

Array

Problem Name	Difficulty
0001-two-sum	Easy
0015-3sum	Medium
0039-combination-sum	Medium
0051-n-queens	Hard
0053-maximum-subarray	Medium
0055-jump-game	Medium
0075-sort-colors	Medium
0078-subsets	Medium
0121-best-time-to-buy-and-sell-stock	Easy
0122-best-time-to-buy-and-sell-stock-ii	Medium
0209-minimum-size-subarray-sum	Medium
0494-target-sum	Medium
0560-subarray-sum-equals-k	Medium
0916-word-subsets	Medium
1282-group-the-people-given-the-group-size-they-belong-to	Medium
1295-find-numbers-with-even-number-of-digits	Easy
1710-maximum-units-on-a-truck	Easy
1828-queries-on-number-of-points-inside-a-circle	Medium
2395-find-subarrays-with-equal-sum	Easy
2597-the-number-of-beautiful-subsets	Medium

Backtracking

Problem Name	Difficulty
0039-combination-sum	Medium
0051-n-queens	Hard
0078-subsets	Medium
0494-target-sum	Medium
2597-the-number-of-beautiful-subsets	Medium

Bit Manipulation

Problem Name	Difficulty
0078-subsets	Medium

Hash Table

Problem Name	Difficulty
0001-two-sum	Easy
0535-encode-and-decode-tinyurl	Medium
0560-subarray-sum-equals-k	Medium
0916-word-subsets	Medium
1282-group-the-people-given-the-group-size-they-belong-to	Medium
2395-find-subarrays-with-equal-sum	Easy
2597-the-number-of-beautiful-subsets	Medium

String

Problem Name	Difficulty
0535-encode-and-decode-tinyurl	Medium
0916-word-subsets	Medium
1143-longest-common-subsequence	Medium
1758-minimum-changes-to-make-alternating-binary-string	Easy
1784-check-if-binary-string-has-at-most-one-segment-of-ones	Easy
1880-check-if-word-equals-summation-of-two-words	Easy
2120-execution-of-all-suffix-instructions-staying-in-a-grid	Medium

Dynamic Programming

Problem Name	Difficulty
0053-maximum-subarray	Medium
0055-jump-game	Medium
0121-best-time-to-buy-and-sell-stock	Easy
0122-best-time-to-buy-and-sell-stock-ii	Medium
0494-target-sum	Medium
1137-n-th-tribonacci-number	Easy
1143-longest-common-subsequence	Medium
2597-the-number-of-beautiful-subsets	Medium

Linked List

Problem Name	Difficulty
0019-remove-nth-node-from-end-of-list	Medium
0024-swap-nodes-in-pairs	Medium
0082-remove-duplicates-from-sorted-list-ii	Medium
0083-remove-duplicates-from-sorted-list	Easy
0114-flatten-binary-tree-to-linked-list	Medium
0237-delete-node-in-a-linked-list	Medium
2095-delete-the-middle-node-of-a-linked-list	Medium

Two Pointers

Problem Name	Difficulty
0015-3sum	Medium
0019-remove-nth-node-from-end-of-list	Medium
0075-sort-colors	Medium
0082-remove-duplicates-from-sorted-list-ii	Medium
2095-delete-the-middle-node-of-a-linked-list	Medium

Recursion

Problem Name	Difficulty
0024-swap-nodes-in-pairs	Medium

Database

Problem Name	Difficulty
0584-find-customer-referee	Easy
0595-big-countries	Easy
1683-invalid-tweets	Easy
1757-recyclable-and-low-fat-products	Easy

Tree

Problem Name	Difficulty
0114-flatten-binary-tree-to-linked-list	Medium
0230-kth-smallest-element-in-a-bst	Medium

Depth-First Search

Problem Name	Difficulty
0114-flatten-binary-tree-to-linked-list	Medium
0230-kth-smallest-element-in-a-bst	Medium

Binary Search Tree

Problem Name	Difficulty
0209-minimum-size-subarray-sum	Medium
0230-kth-smallest-element-in-a-bst	Medium

Binary Tree

Problem Name	Difficulty
0114-flatten-binary-tree-to-linked-list	Medium
0230-kth-smallest-element-in-a-bst	Medium

Stack

Problem Name	Difficulty
0114-flatten-binary-tree-to-linked-list	Medium

Divide and Conquer

Problem Name	Difficulty
0053-maximum-subarray	Medium

Greedy

Problem Name	Difficulty
0055-jump-game	Medium
0122-best-time-to-buy-and-sell-stock-ii	Medium
1282-group-the-people-given-the-group-size-they-belong-to	Medium
1710-maximum-units-on-a-truck	Easy

Prefix Sum

Problem Name	Difficulty
0209-minimum-size-subarray-sum	Medium
0560-subarray-sum-equals-k	Medium

Sorting

Problem Name	Difficulty
0015-3sum	Medium
0075-sort-colors	Medium
1710-maximum-units-on-a-truck	Easy
2597-the-number-of-beautiful-subsets	Medium

Sliding Window

Problem Name	Difficulty
0209-minimum-size-subarray-sum	Medium

Math

Problem Name	Difficulty
0263-ugly-number	Easy
0507-perfect-number	Easy
1137-n-th-tribonacci-number	Easy
1295-find-numbers-with-even-number-of-digits	Easy
1828-queries-on-number-of-points-inside-a-circle	Medium
2597-the-number-of-beautiful-subsets	Medium

Combinatorics

Problem Name	Difficulty
2597-the-number-of-beautiful-subsets	Medium

Memoization

Problem Name	Difficulty
1137-n-th-tribonacci-number	Easy

Design

Problem Name	Difficulty
0535-encode-and-decode-tinyurl	Medium

Hash Function

Problem Name	Difficulty
0535-encode-and-decode-tinyurl	Medium

Simulation

Problem Name	Difficulty
2120-execution-of-all-suffix-instructions-staying-in-a-grid	Medium

Geometry

Problem Name	Difficulty
1828-queries-on-number-of-points-inside-a-circle	Medium