the daily algorithm exercises
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no Title Tag Coefficient of difficulty
1 Two Sum Array HashTable Easy
2 Add Two Numbers LinkedList Math Medium
3 Longest Substring Without Repeating Characters Hash Table Two Pointers String Medium
4 Median of Two Sorted Arrays Array Binary Search Divide Conquer Hard
5 Longest Palindrome Substring String Medium
6 ZigZag Conversion String Medium
7 Reverse Integer Math Easy
8 String to Integer (atoi) Math String Medium
9 Palindrome Number Math Easy
10 Regular Expression Matching String Dynamic Programming Backtracking Hard
11 Container With Most Water Array Two Pointers Medium
12 Integer to Roman Math String Medium
13 Roman to Integer Math String Easy
14 Longest Common Prefix String Easy
15 3Sum Array Two Pointers Medium
16 3Sum Closest Array Two Pointers Medium
17 Letter Combinations of a Phone Number String Backtracking Medium
18 4Sum Array Two Pointers Medium
19 Remove Nth Node From End of List ListedList Two Pointers Medium
20 Valid Parentheses String Stack Easy
21 Merge Two Sorted Lists LinkedList Easy
22 Generate Parentheses String BackTracking Medium
23 Merge Kth Sorted Lists LinkedList Divide Conquer Heap Hard
24 Swap Nodes in Pairs LinkedList Medium
25 Reverse Nodes in k-Group LinkedList Hard
26 Remove Duplicates From Sorted Array Array Two Pointers Easy
27 Remove Element Array Two Pointers Easy
28 Implement strStr() String Two Pointers Easy
29 Divide Two Integers Math Binary Search Medium
30 Substring with Concatenation of All Words String HashTable Two Pointers Hard
31 Next Permutation Array Medium
32 Longest Valid Parentheses String Dynamic Programming Medium
33 Search in Rotated Sorted Array Array Binary Search Medium
34 Search for a Range Array Binary Search Medium
35 Search Insert Position Array Binary Search Easy
36 Valid Sudoku Hash Table Medium
37 Sudoku Solver Hash Table Backtracking Hard
38 Count and Say String Easy
39 Combination Sum Array Backtracking Medium
40 Combination Sum II Array Backtracking Medium
41 First Missing Positive Array Hard
42 Trapping Rain Water Array Two Pointers Stack Hard
43 Multiply Strings Math String Medium
44 Wildcard Matching String Dynamic Programing Medium
45 Jump Game II Array Greedy Medium
46 Permutation Backtracking Medium
47 Permutation II Backtracking Array Medium
48 Rotate Image Array Medium
49 Group Anagrams Hash Table String Medium
50 Pow(x, n) Math Binary Search Medium
51 N-Queens Backtracking Hard
52 N-Queens II Backtracking Hard
53 Maximum Subarray Dynamic Programing Array Divide and Conquer Easy
54 Spiral Matrix Array Medium
55 Jump Game Array Greedy Medium
56 Merge Intervals Array Sort Medium
57 Insert Interval Array Sort Hard
58 Length of Last Word String Easy
59 Spiral Matrix II Array Medium
60 Permutation Sequence Backtracking Math Medium
61 Rotate List LinkedList Two Pointers Medium
62 Unique Paths Dynamic Programing Array Medium
63 Unique Paths II Dynamic Programing Array Medium
64 Minimum Path Sum Dynamic Programing Array Medium
65 Valid Number Math String Hard
66 Plus One Array Math Easy
67 Add Binary Math String Easy
68 Text Justification String Hard
69 Sqrt(x) Math Binary Search Easy
70 Climbing Stairs Dynamic Programing Easy
71 Simplify Path String Stack Medium
72 Edit Distance String Dynamic Programming Hard
73 Set Matrix Zeroes Array Medium
74 Search a 2D Matrix Array Binary Search Medium
75 Sort Colors Array Two Pointers Sort Medium
76 Minimum Window Substring String Hash Table Two Poniters Hard
77 Combinations Backtracking Medium
78 Subsets Backtracking Array Bit manipulation Medium
79 Word Search Array Backtracking Medium
80 Remove Duplicates from Sorted Array II Array Two Pointers Medium
83 Remove Duplicates from Sorted List Linked List Easy
84 Largest Rectangle in Histogram Stack Array Hard
88 Merge Sorted Array Array Two Pointer Easy
89 Gray Code Backtracking Medium
94 Binary Tree Inorder Traversal Hash Tabke Stack Tree Medium
98 Validate Binary Search Tree Tree Depth-First Search Medium
100 Same Tree Tree Depth-First Search Easy
104 Maximum Depth of Binary Tree Tree Depth-First Search Easy
105 Construct Binary Tree from Preorder and Inorder Traversal Array Tree Depth-First Search Medium
106 Construct Binary Tree from Inorder and Postorder Traversal Array Tree Depth-First Search Medium
108 Convert Sorted Array to Binary Search Tree Tree Depth-First Search Easy
110 Balanced Binary Tree Tree Depth-First Search Easy
111 Minimum Depth of Binary Tree Tree Depth-First Search BFS Easy
112 Path Sum Tree Depth-First Search Easy
113 Path Sum II Tree Depth-First Search Medium
118 Pascal's Triangle Array Easy
119 Pascal's Triangle II Array Easy
120 Triangle Array Dynamic Programing Medium
121 Best Time to Buy and Sell Stock Array Dynamic-Programming Easy
122 Best Time to Buy and Sell Stock II Array Greedy Easy
125 Valid Palindrome String Two Pointers Easy
130 Surrounded Regions DFS BFS Union-Find Medium
139 Word Break Dynamic Programing Medium
136 Single Number Bit manipulation Easy
148 Sort List Linked List Sort Medium
155 Min Stack Stack Design Easy
160 Intersection of Two Linked Lists LinkedList Easy
169 Majority Element Array Bit manipulation Divide and Conquer Easy
198 House Robber Dynamic Programming Easy
199 Binary Tree Right Side View Tree DFS BFS Medium
215 Kth Largest Element in an Array Divide and Conquer Heap Medium
242 Valid Anagram Hash Table Sort Easy
263 Ugly Number Math Easy
263 Find Median from Data Stream Heap Dessign Hard
303 Range Sum Query - Immutable Dynamic Programing Easy
304 Range Sum Query 2D - Immutable Dynamic Programing Medium
307 Range Sum Query - Mutable Binary Indexed Tree Segment Tree Medium
309 Best Time to Buy and Sell Stock with Cooldown Dynamic Programing Medium
344 Reverse String String Easy
387 First Unique Character in a String Hash Table String Easy
421 Maximum XOR of Two Numbers in an Array Trie Medium
437 Path Sum II Tree Easy
461 Hamming Distance Bit manipulation Easy
494 Target Sum Dynamic Programing DFS Medium
530 Minimum Absolute Difference in BST Binary Search Tree Easy
530 K-diff Pairs in an Array Array Two Pointers Easy
554 Brick Wall Hash Table Medium
557 Reverse Words in a String III String Easy
693 Binary Number with Alternating Bits) Bit manipulation Easy
724 Find Pivot Index Array Easy
725 Split Linked List in Parts Linked List Medium
738 Monotone Increasing Digits Greedy Medium
739 Daily Temperatures Hash Table Array Medium
743 Network Delay Time Heap DFS BFS Graph Medium
766 Toeplitz Matrix Array Easy
767 Reorganize String String Heap Greedy Sort Medium
804 Unique Morse Code Words String Easy
842 Split Array into Fibonacci Sequence String Backtracking Greedy Medium
844 Backspace String Compare Stack Two Pointers Easy
896 Monotonic Array Array Easy
897 Increasing Binary Search Tree Binary Search Tree Depth-first Search Easy
921 Minimum Add to Make Parentheses Valid String Stack Medium
922 Sort Array By Parity II Array Easy