/*# Java-Data-Structures-and-Algorithms Optimized Java solutions for 150+ DSA patterns with documented Time/Space complexity analysis.

🛠️ Tech Stack & Standards

• Language: Java
• Concepts: Arrays, Strings, HashMaps, Two Pointers, Trees, Graphs, Dynamic Programming.
• Documentation: Every solution includes a Big-O analysis header.
• Style: Following Google Java Style Guide for clean, readable code.

🏗️ Architecture: Linked Lists

To demonstrate Separation of Concerns, the Linked List section is implemented using a modular approach:

• Node.java: The data model and reference structure.
• LinkListSingly.java: The core algorithm implementation (Logic).
• LL.java: The driver class for execution and test cases.

📊 Progress Tracker

#	Problem	Topic	Complexity	Status
1	Two Sum	Hash Table	$O(n^2)$ Time, $O(1)$ Space	✅
2	Valid Palindrome	Two Pointers	$O(n)$ Time, $O(1)$ Space	✅
3	Merge Sorted Array	Two Pointers	$O(m+n)$ Time, $O(1)$ Space	✅
4	Remove Element	Two Pointers	$O(n)$ Time, $O(1)$ Space	✅
5	Remove Duplicates	Two Pointers	$O(n)$ Time, $O(1)$ Space	✅
6	Majority Element	Two Pointers	$O(n log n)$ Time, $O(n)$ Space	✅
7	Length Of Last Word	One Pointer	$O(n)$ Time , $O(n)$ Space	✅
8	Singly Linked List	Node • Logic • Driver	$O(n)$ Search, $O(1)$ Head Ops	✅
9	Linked List Cycle	slow and fast Pointer	$O(n)$ Time , $O(1)$ Space	✅
10	Reverse Words In String	Two Pointers String	$O(n)$ Time , $O(n)$ Space	✅
11	Reverse Linked List II	Partial Reversal	$O(n)$ Time , $O(1)$ Space	✅
12	Merge Two Sorted Lists	Linked List	$O(n+m)$ Time , $O(1)$ Space	✅
13	Linked List Cycle II	slow and fast pointer	$O(n)$ Time , $O(1)$ Space	✅
14	First Occurence In String	Sliding window	$O(n \cdot m)$ Time , $O(n)$ Space	✅
15	Longest Common Prefix In String	Strings scanning	$O(n)$ Time , $O(1)$ Space	✅
16	Two Sum II	Two Pointers	$O(n)$ Time, $O(1)$ Space	✅
17	Three Sum	Two Pointers/sorting	$O(n^2)$ Time, $O(1)$ Space	✅
18	Palindrome Number	Math / Reversal	$O(\log n)$ Time, $O(1)$ Space	✅
19	BinarySearch Search	Divide and conquer	$O(log n)$ Time, $O(1)$ Space	✅
20	PlusOne Number	Math / Arrays	$O(n)$ Time, $O(n)$ Space	✅
21	Add Two Numbers	Linked List/Math	$O(max(l1,l2))$ Time , $O(max(l1,l2))$ Space	✅
22	SearchIn2DMatrix	BinarySearch Search	$O(log (m*n))$ Time, $O(1)$ Space	✅
23	Roman To Int	Arrays /Strings	$O(n)$ Time, $O(1)$ Space	✅
24	Int To Roman	Arrays /Strings	$O(1)$ Time, $O(1)$ Space	✅
25	Square Root	Math	$O(\sqrt{n})$ Time, $O(1)$ Space	✅
26	Power Function	Math	$O(log(n)$ Time, $O(1)$ Space	✅
27	Min Sub Array	Math	$O(log(n)$ Time, $O(1)$ Space	✅
28	Longest Sub String	Math/HashSet	$O((n)$ Time, $O(min(m,n)$ Space	✅
29	Find All Sub String	Math/HashSet	$O((n)$ Time, $O(m)$ Space	✅
30	Max Area	Array/Two Pointer Approach	$O((n)$ Time, $O(1)$ Space	✅
31	Spiral Matrix	Array/Matrix	$O((MXN)$ Time, $O(1)$ Space	✅
32	Is Valid Sudoku	Array/Matrix	$O((N^2)$ Time, $O(1)$ Space	✅
33	Can construct	HashMap	$O((MXN)$ Time, $O(k)$ Space where k is 1 to 26	✅
33	Isomorphic	HashMap	$O((N)$ Time, $O(k)$ Space	✅
34	Word Pattern	HashMap	$O((N)$ Time, $O(N)$ Space where n is same as take n time and space will also take same.	✅
35	Happy Number	Linked List/Math	$O(log n)$ Time , $O(1)$ Space	✅
36	Group Anagrams	Hash Table / String	$O(N \cdot K)$ Time, $O(N \cdot K)$ Space	✅
37	Contains Duplicate II	Hash Table / Sliding Window	$O(n)$ Time, $O(\min(n, k))$ Space	✅
38	SummaryRanges	Two Pointer /Arrays	$O(n)$ Time, $O(1)$ Space	✅
39	Merge Intervals	Two Pointer /Arrays/Greedy Approach	$O(n(logn))$ Time, $O(logn)$ Space	✅
40	Insert Interval	Two Pointer /Arrays/Greedy Approach	$O(n)$ Time, $(n)$ Space	✅
41	Insert Interval	Two Pointer /Arrays/Greedy Approach	$O(n(logn))$ Time, $O(logn)$ Space	✅
42	Jump One	Arrays/Greedy Approach	$O(n(logn))$ Time, $O(logn)$ Space	✅
43	MaxDepth	BinarySearch Tree / Math	$O(n)$ Time, $O(n)$ Space	✅
44	Same Tree	BinarySearch Tree / Recursion	$O(n)$ Time, $O(n)$ Space	✅
45	Invert Tree	BinarySearch Tree / Recursion	$O(n)$ Time,Space : Best $O(logn)$, Worst $O(n)$	✅
46	Sysmmetric Tree	BinarySearch Tree / Recursion	$O(n)$ Time, $O(n)$ space	✅
47	Construct A Tree From Both Preoder And Inorder	BinarySearch Tree / Recursion/HashMap	$O(n)$ Time, $O(n)$ space	✅
48	Construct A Tree From Both Postorder And Inorder	BinarySearch Tree / Recursion/HashMap	$O(n)$ Time, $O(n)$ space	✅
49	Populating Next Right Pointers II	BinarySearch Tree / Iterative/LinkList	$O(n)$ Time, $O(1)$ space	✅
50	Flatten BinarySearch Tree To LinkedList	BinarySearch Tree /Recursion Using preorder /LinkList	$O(n)$ Time, $O(n)$ space	✅
51	Path Sum Solver	BinarySearch Tree /Recursion	$O(n)$ Time, $O(n)$ space	✅
52	Jump To End II	Array/Greedy	$O(n)$ Time, $O(1)$ space	✅
53	Sum To Root Leaf	BinarySearch Tree /Recursion /DFS	$O(n)$ Time, $O(n)$ space	✅
54	SubString Concatenation	String /HashMap /ArrayList	$O(n)$ Time, $O(m *w)$ space	✅
55	Path Sum Solver II	BinarySearch Tree/DFS /Recursion	$O(n)$ Time, $O(n)$ space	✅
56	BinarySearch Adder	Bit Manupulation / Math	$O(max(n,m))$ Time, $O(max(n,m))$ space	✅
57	Reverse Bits	Bit Manupulation /Divide and Conquer	$O(1)$ Time, $O(1)$ space	✅
58	Hamming Weight calculator	Bit Manupulation /Bitwise operator	$O(1)$ Time, $O(1)$ space	✅
59	Single Number	Bit Manupulation /Bitwise operator /XoR operator	$O(n)$ Time, $O(1)$ space	✅
60	Single Number II	Bit Manupulation /Bitwise operator /XoR operator	$O(n)$ Time, $O(1)$ space	✅
61	Range Bitwise And	Bit Manupulation /Bitwise operator	$O(\logn)$ Time, $O(1)$ space	✅
62	Count Trailing Zeroes	Math	$O(log_5 n)$ Time, $O(1)$ space	✅
63	Max Points in the (X, Y) plane	Math	$O(n^2)$ Time, $O(n)$ space	✅
64	Merge K Sorted Lists	Math/Divide and Conquer /LinkedList	$O(n log k)$ Time, $O( log k)$ space	✅
65	Kadane's Algorithm	Math/Kadene's Algorithm	$O(n)$ Time, $O(1)$ space	✅
66	Peak Finder	Math/Binary Search/ Recursive	$O(log n)$ Time, $O(log n)$ space	✅
67	Search In Rotated Sorted Array	Math/Binary Search/ Recursive	$O(log n)$ Time, $O(log n)$ space	✅
68	Return First And Last Target In Array	Math/Binary Search/ Recursive	$O(log n)$ Time, $O(log n)$ space	✅
69	Find Minimum In Rotated Array	Math/Binary Search/ Recursive	$O(log n)$ Time, $O(log n)$ space	✅
70	Find The Median From Two Sorted Array	Math/Binary Search/Recursive/Iterative	$O(log(min(m, n))$ Time, $O(1)$ space	✅
71	Valid Parentheses Check	Stack	$O(n)$ Time, $O(1)$ space	✅
72	Unix Style Path Simplifier	Stack /String	$O(n)$ Time, $O(n)$ space	✅
73	Reverse Polish Notation	Stack /String /Switch	$O(n)$ Time, $O(n)$ space	✅
74	Stack Implementation Like pop(), push(), MinStack() etc	Stack/ArrayList	$O(1)$ Time, $O(n)$ space	✅
75	Basic Calculator Using Stack	Stack/ArrayDeque/Deque	$O(n)$ Time, $O(n)$ space	✅
76	Find Kth Element In Unsorted Array	Heap/PriorityQueue	$O(n (log k))$ Time, $O(k)$ space	✅
77	Find The Sum of SubArray Using Kadane's Algo	Kadanes Algorithm/Math	$O(n))$ Time, $O(1)$ space	✅
78	Rotate Image By 90 Degree	Array/Matrix	$O(n^2)$ Time, $O(1)$ Space	✅
79	Array To Binary seatch Tree Conversion	Array/Binary Search Tree/ Recursion	$O(n)$ Time, $O(log(n))$ Space	✅
80	Jump II	Array	$O(n)$ Time,$O(1)$ Space	✅
81	Binary Search Iterator	Binary Tree, Recursion	$O(1)$ Time,$O(h)$ Space	✅
82	Reverse Nodes In K Group	LinkedList, Recursion	$O(n)$ Time,$O(n/k)$ Space	✅
83	H Index Finder	Array,Bucket Sort	$O(n)$ Time,$O(n)$ Space	✅

🚀 How to Use

Each folder is categorized by data structure. Navigate to a folder and open the .java file to see the logic and performance analysis in the comments. */