Algorithm Notes

Algorithm Notes
Algorithm Basics
Algorithm Basics
- 01 Sorting
  01 Sorting
- 02 Binary Search
  02 Binary Search
  - Example: Binary Search Float
- 03 High Precision
  03 High Precision
- 04 Partial Sum
  04 Partial Sum
- 05 Double Pointer
  05 Double Pointer
- 06 Bit Operations
  06 Bit Operations
- 07 Discretization
  07 Discretization
- 08 Interval Merging
  08 Interval Merging
Data Structures
Data Structures
- 01 Linked List
  01 Linked List
- 02 Stack and Queue
  02 Stack and Queue
- 03 KMP
  03 KMP
- 04 Trie
  04 Trie
- 05 Disjoint Set
  05 Disjoint Set
- 06 Heap
  06 Heap
- 07 Hash Table
  07 Hash Table
- 08 Binary Indexed Tree
  08 Binary Indexed Tree
- 09 Segment Tree
  09 Segment Tree
- Special Topic STL
  Special Topic STL
Dynamic Programming
Dynamic Programming
- 01 Backpack Problem
  01 Backpack Problem
- 02 Linear DP
  02 Linear DP
- 03 Interval DP
  03 Interval DP
- 04 Counting DP
  04 Counting DP
  - Integer partition
- 05 Digital Counting DP
  05 Digital Counting DP
- 06 States Compression DP
  06 States Compression DP
  - Shortest Hamilton Distance
  - Mondriaan dream
- 07 Tree DP
  07 Tree DP
  - Example: Prom without a Boss
- 08 Memorization Search
  08 Memorization Search
  - Example: Snowboarding
Graph and Search
Graph and Search
- 01 DFS BFS
  01 DFS BFS
- 02 Graph Tree Basics
  02 Graph Tree Basics
- 03 Shortest Path
  03 Shortest Path
- 04 Minimum Spanning Tree
  04 Minimum Spanning Tree
- 05 Bipartite Graph
  05 Bipartite Graph
- 06 Network Flow
  06 Network Flow
- 07 Tree Basics
  07 Tree Basics
Greedy Methods
Greedy Methods
- 01 Interval Problems
  01 Interval Problems
- 02 Huffman Coding
  02 Huffman Coding
Leetcode
Leetcode
- Contest Solutions
- 0001 0099
  0001 0099
  - 0001 two sum
    
    0001 two sum
  - 0003 longest substring without repeating characters
    
    0003 longest substring without repeating characters
  - 0006 zigzag conversion
    
    0006 zigzag conversion
  - 0008 string to integer atoi
    
    0008 string to integer atoi
  - 0015 3sum
    
    0015 3sum
  - 0017 letter combinations of a phone number
    
    0017 letter combinations of a phone number
  - 0018 4sum
    
    0018 4sum
  - 0019 remove nth node from end of list
    
    0019 remove nth node from end of list
  - 0020 valid parentheses
    
    0020 valid parentheses
  - 0021 merge two sorted lists
    
    0021 merge two sorted lists
  - 0023 merge k sorted lists
    
    0023 merge k sorted lists
  - 0024 swap nodes in pairs
    
    0024 swap nodes in pairs
  - 0026 remove duplicates from sorted array
    
    0026 remove duplicates from sorted array
  - 0027 remove element
    
    0027 remove element
  - 0028 find the index of the first occurrence in a string
    
    0028 find the index of the first occurrence in a string
  - 0031 next permutation
    
    0031 next permutation
  - 0032 longest valid parentheses
    
    0032 longest valid parentheses
  - 0033 search in rotated sorted array
    
    0033 search in rotated sorted array
  - 0034 find first and last position of element in sorted array
    
    0034 find first and last position of element in sorted array
  - 0035 search insert position
    
    0035 search insert position
  - 0036 valid sudoku
    
    0036 valid sudoku
  - 0037 sudoku solver
    
    0037 sudoku solver
  - 0039 combination sum
    
    0039 combination sum
  - 0040 combination sum ii
    
    0040 combination sum ii
  - 0041 first missing positive
    
    0041 first missing positive
  - 0042 trapping rain water
    
    0042 trapping rain water
  - 0045 jump game ii
    
    0045 jump game ii
  - 0046 permutations
    
    0046 permutations
  - 0047 permutations ii
    
    0047 permutations ii
  - 0051 n queens
    
    0051 n queens
  - 0052 n queens ii
    
    0052 n queens ii
  - 0053 maximum subarray
    
    0053 maximum subarray
  - 0054 spiral matrix
    
    0054 spiral matrix
  - 0055 jump game
    
    0055 jump game
  - 0056 merge intervals
    
    0056 merge intervals
  - 0059 spiral matrix ii
    
    0059 spiral matrix ii
  - 0062 unique paths
    
    0062 unique paths
  - 0063 unique paths ii
    
    0063 unique paths ii
  - 0070 climbing stairs
    
    0070 climbing stairs
  - 0071 simplify path
    
    0071 simplify path
  - 0072 edit distance
    
    0072 edit distance
  - 0074 search a 2d matrix
    
    0074 search a 2d matrix
  - 0076 minimum window substring
    
    0076 minimum window substring
  - 0077 combinations
    
    0077 combinations
  - 0078 subsets
    
    0078 subsets
  - 0081 search in rotated sorted array ii
    
    0081 search in rotated sorted array ii
  - 0084 largest rectangle in histogram
    
    0084 largest rectangle in histogram
  - 0085 maximal rectangle
    
    0085 maximal rectangle
  - 0086 partition list
    
    0086 partition list
  - 0090 subsets ii
    
    0090 subsets ii
  - 0091 decode ways
    
    0091 decode ways
  - 0092 reverse linked list ii
    
    0092 reverse linked list ii
  - 0093 restore ip addresses
    
    0093 restore ip addresses
  - 0094 binary tree inorder traversal
    
    0094 binary tree inorder traversal
  - 0096 unique binary search trees
    
    0096 unique binary search trees
  - 0098 validate binary search tree
    
    0098 validate binary search tree
- 0100 0199
  0100 0199
  - 0100 same tree
    
    0100 same tree
  - 0101 symmetric tree
    
    0101 symmetric tree
  - 0102 binary tree level order traversal
    
    0102 binary tree level order traversal
  - 0103 binary tree zigzag level order traversal
    
    0103 binary tree zigzag level order traversal
  - 0104 maximum depth of binary tree
    
    0104 maximum depth of binary tree
  - 0105 construct binary tree from preorder and inorder traversal
    
    0105 construct binary tree from preorder and inorder traversal
  - 0106 construct binary tree from inorder and postorder traversal
    
    0106 construct binary tree from inorder and postorder traversal
  - 0110 balanced binary tree
    
    0110 balanced binary tree
  - 0111 minimum depth of binary tree
    
    0111 minimum depth of binary tree
  - 0112 path sum
    
    0112 path sum
  - 0113 path sum ii
    
    0113 path sum ii
  - 0120 triangle
    
    0120 triangle
  - 0121 best time to buy and sell stock
    
    0121 best time to buy and sell stock
  - 0122 best time to buy and sell stock ii
    
    0122 best time to buy and sell stock ii
  - 0123 best time to buy and sell stock iii
    
    0123 best time to buy and sell stock iii
  - 0126 word ladder ii
    
    0126 word ladder ii
  - 0127 word ladder
    
    0127 word ladder
  - 0128 longest consecutive sequence
    
    0128 longest consecutive sequence
  - 0130 surrounded regions
    
    0130 surrounded regions
  - 0131 palindrome partitioning
    
    0131 palindrome partitioning
  - 0133 clone graph
    
    0133 clone graph
  - 0134 gas station
    
    0134 gas station
  - 0135 candy
    
    0135 candy
  - 0136 single number
    
    0136 single number
  - 0137 single number ii
    
    0137 single number ii
  - 0139 word break
    
    0139 word break
  - 0141 linked list cycle
    
    0141 linked list cycle
  - 0142 linked list cycle ii
    
    0142 linked list cycle ii
  - 0144 binary tree preorder traversal
    
    0144 binary tree preorder traversal
  - 0145 binary tree postorder traversal
    
    0145 binary tree postorder traversal
  - 0146 lru cache
    
    0146 lru cache
  - 0148 sort list
    
    0148 sort list
  - 0150 evaluate reverse polish notation
    
    0150 evaluate reverse polish notation
  - 0151 reverse words in a string
    
    0151 reverse words in a string
  - 0153 find minimum in rotated sorted array
    
    0153 find minimum in rotated sorted array
  - 0154 find minimum in rotated sorted array ii
    
    0154 find minimum in rotated sorted array ii
  - 0160 intersection of two linked lists
    
    0160 intersection of two linked lists
  - 0162 find peak element
    
    0162 find peak element
  - 0188 best time to buy and sell stock iv
    
    0188 best time to buy and sell stock iv
  - 0191 number of 1 bits
    
    0191 number of 1 bits
  - 0198 house robber
    
    0198 house robber
- 0200 0299
  0200 0299
  - 0200 number of islands
    
    0200 number of islands
  - 0201 bitwise and of numbers range
    
    0201 bitwise and of numbers range
  - 0202 happy number
    
    0202 happy number
  - 0203 remove linked list elements
    
    0203 remove linked list elements
  - 0206 reverse linked list
    
    0206 reverse linked list
  - 0207 course schedule
    
    0207 course schedule
  - 0208 implement trie prefix tree
    
    0208 implement trie prefix tree
  - 0209 minimum size subarray sum
    
    0209 minimum size subarray sum
  - 0210 course schedule ii
    
    0210 course schedule ii
  - 0212 word search ii
    
    0212 word search ii
  - 0213 house robber ii
    
    0213 house robber ii
  - 0215 kth largest element in an array
    
    0215 kth largest element in an array
  - 0216 combination sum iii
    
    0216 combination sum iii
  - 0222 count complete tree nodes
    
    0222 count complete tree nodes
  - 0225 implement stack using queues
    
    0225 implement stack using queues
  - 0226 invert binary tree
    
    0226 invert binary tree
  - 0231 power of two
    
    0231 power of two
  - 0232 implement queue using stacks
    
    0232 implement queue using stacks
  - 0235 lowest common ancestor of a binary search tree
    
    0235 lowest common ancestor of a binary search tree
  - 0236 lowest common ancestor of a binary tree
    
    0236 lowest common ancestor of a binary tree
  - 0239 sliding window maximum
    
    0239 sliding window maximum
  - 0242 valid anagram
    
    0242 valid anagram
  - 0257 binary tree paths
    
    0257 binary tree paths
  - 0260 single number iii
    
    0260 single number iii
  - 0264 ugly number ii
    
    0264 ugly number ii
  - 0268 missing number
    
    0268 missing number
  - 0269 alien dictionary
    
    0269 alien dictionary
  - 0290 word pattern
    
    0290 word pattern
  - 0291 word pattern ii
    
    0291 word pattern ii
  - 0295 find median from data stream
    
    0295 find median from data stream
  - 0297 serialize and deserialize binary tree
    
    0297 serialize and deserialize binary tree
- 0300 0399
  0300 0399
  - 0300 longest increasing subsequence
    
    0300 longest increasing subsequence
  - 0303 range sum query immutable
    
    0303 range sum query immutable
  - 0314 binary tree vertical order traversal
    
    0314 binary tree vertical order traversal
  - 0316 remove duplicate letters
    
    0316 remove duplicate letters
  - 0322 coin change
    
    0322 coin change
  - 0325 maximum size subarray sum equals k
    
    0325 maximum size subarray sum equals k
  - 0329 longest increasing path in a matrix
    
    0329 longest increasing path in a matrix
  - 0337 house robber iii
    
    0337 house robber iii
  - 0343 integer break
    
    0343 integer break
  - 0344 reverse string
    
    0344 reverse string
  - 0347 top k frequent elements
    
    0347 top k frequent elements
  - 0349 intersection of two arrays
    
    0349 intersection of two arrays
  - 0359 logger rate limiter
    
    0359 logger rate limiter
  - 0362 design hit counter
    
    0362 design hit counter
  - 0371 sum of two integers
    
    0371 sum of two integers
  - 0376 wiggle subsequence
    
    0376 wiggle subsequence
  - 0377 combination sum iv
    
    0377 combination sum iv
  - 0380 insert delete getrandom o1
    
    0380 insert delete getrandom o1
  - 0383 ransom note
    
    0383 ransom note
  - 0395 longest substring with at least k repeating characters
    
    0395 longest substring with at least k repeating characters
  - 0399 evaluate division
    
    0399 evaluate division
- 0400 0499
  0400 0499
  - 0404 sum of left leaves
    
    0404 sum of left leaves
  - 0406 queue reconstruction by height
    
    0406 queue reconstruction by height
  - 0410 split array largest sum
    
    0410 split array largest sum
  - 0416 partition equal subset sum
    
    0416 partition equal subset sum
  - 0421 maximum xor of two numbers in an array
    
    0421 maximum xor of two numbers in an array
  - 0435 non overlapping intervals
    
    0435 non overlapping intervals
  - 0450 delete node in a bst
    
    0450 delete node in a bst
  - 0452 minimum number of arrows to burst balloons
    
    0452 minimum number of arrows to burst balloons
  - 0454 4sum ii
    
    0454 4sum ii
  - 0455 assign cookies
    
    0455 assign cookies
  - 0459 repeated substring pattern
    
    0459 repeated substring pattern
  - 0460 lfu cache
    
    0460 lfu cache
  - 0467 unique substrings in wraparound string
    
    0467 unique substrings in wraparound string
  - 0474 ones and zeroes
    
    0474 ones and zeroes
  - 0476 number complement
    
    0476 number complement
  - 0491 non decreasing subsequences
    
    0491 non decreasing subsequences
  - 0494 target sum
    
    0494 target sum
  - 0496 next greater element i
    
    0496 next greater element i
- 0500 0599
  0500 0599
  - 0500 minimum absolute difference in bst
    
    0500 minimum absolute difference in bst
  - 0503 next greater element ii
    
    0503 next greater element ii
  - 0509 fibonacci number
    
    0509 fibonacci number
  - 0513 find bottom left tree value
    
    0513 find bottom left tree value
  - 0518 coin change ii
    
    0518 coin change ii
  - 0530 minimum absolute difference in bst
    
    0530 minimum absolute difference in bst
  - 0541 reverse string ii
    
    0541 reverse string ii
  - 0556 next greater element iii
    
    0556 next greater element iii
  - 0560 subarray sum equals k
    
    0560 subarray sum equals k
- 0600 0699
  0600 0699
  - 0617 merge two binary trees
    
    0617 merge two binary trees
  - 0639 decode ways ii
    
    0639 decode ways ii
  - 0654 maximum binary tree
    
    0654 maximum binary tree
  - 0662 maximum width of binary tree
    
    0662 maximum width of binary tree
  - 0669 trim a binary search tree
    
    0669 trim a binary search tree
  - 0673 number of longest increasing subsequence
    
    0673 number of longest increasing subsequence
  - 0674 longest continuous increasing subsequence
    
    0674 longest continuous increasing subsequence
- 0700 0799
  0700 0799
  - 0700 search in a binary search tree
    
    0700 search in a binary search tree
  - 0703 kth largest element in a stream
    
    0703 kth largest element in a stream
  - 0704 binary search
    
    0704 binary search
  - 0707 design linked list
    
    0707 design linked list
  - 0720 longest word in dictionary
    
    0720 longest word in dictionary
  - 0739 daily temperatures
    
    0739 daily temperatures
  - 0743 network delay time
    
    0743 network delay time
  - 0744 find smallest letter greater than target
    
    0744 find smallest letter greater than target
  - 0746 min cost climbing stairs
    
    0746 min cost climbing stairs
  - 0762 prime number of set bits in binary representation
    
    0762 prime number of set bits in binary representation
  - 0763 partition labels
    
    0763 partition labels
  - 0765 couples holding hands
    
    0765 couples holding hands
  - 0787 cheapest flights within k stops
    
    0787 cheapest flights within k stops
- 0800 0899
  0800 0899
  - 0803 bricks falling when hit
    
    0803 bricks falling when hit
  - 0827 making a large island
    
    0827 making a large island
  - 0839 similar string groups
    
    0839 similar string groups
  - 0851 loud and rich
    
    0851 loud and rich
  - 0860 lemonade change
    
    0860 lemonade change
  - 0862 shortest subarray with sum at least k
    
    0862 shortest subarray with sum at least k
- 0900 0999
  0900 0999
  - 0907 sum of subarray minimums
    
    0907 sum of subarray minimums
  - 0912 sort an array
    
    0912 sort an array
  - 0928 minimize malware spread ii
    
    0928 minimize malware spread ii
  - 0936 stamping the sequence
    
    0936 stamping the sequence
  - 0940 distinct subsequences ii
    
    0940 distinct subsequences ii
  - 0947 most stones removed with same row or column
    
    0947 most stones removed with same row or column
  - 0958 check completeness of a binary tree
    
    0958 check completeness of a binary tree
  - 0962 maximum width ramp
    
    0962 maximum width ramp
  - 0977 squares of a sorted array
    
    0977 squares of a sorted array
  - 0983 minimum cost for tickets
    
    0983 minimum cost for tickets
  - 0987 vertical order traversal of a binary tree
    
    0987 vertical order traversal of a binary tree
  - 0992 subarrays with k different integers
    
    0992 subarrays with k different integers
- 1000 1099
  1000 1099
  - 1000 minimum cost to merge stones
    
    1000 minimum cost to merge stones
  - 1002 find common characters
    
    1002 find common characters
  - 1005 maximize sum of array after k negations
    
    1005 maximize sum of array after k negations
  - 1020 number of enclaves
    
    1020 number of enclaves
  - 1047 remove all adjacent duplicates in string
    
    1047 remove all adjacent duplicates in string
  - 1049 last stone weight ii
    
    1049 last stone weight ii
  - 1094 car pooling
    
    1094 car pooling
- 1100 1199
  1100 1199
  - 1106 parsing a boolean expression
    
    1106 parsing a boolean expression
  - 1109 corporate flight bookings
    
    1109 corporate flight bookings
  - 1124 longest well performing interval
    
    1124 longest well performing interval
  - 1136 parallel courses
    
    1136 parallel courses
  - 1143 longest common subsequence
    
    1143 longest common subsequence
  - 1162 as far from land as possible
    
    1162 as far from land as possible
- 1200 1299
  1200 1299
  - 1234 replace the substring for balanced string
    
    1234 replace the substring for balanced string
- 1300 1399
  1300 1399
  - 1368 minimum cost to make at least one valid path in a grid
    
    1368 minimum cost to make at least one valid path in a grid
  - 1371 find the longest substring containing vowels in even counts
    
    1371 find the longest substring containing vowels in even counts
- 1400 1499
  1400 1499
  - 1438 longest continuous subarray with absolute diff less than or equal to limit
    
    1438 longest continuous subarray with absolute diff less than or equal to limit
- 1500 1599
  1500 1599
  - 1504 count submatrices with all ones
    
    1504 count submatrices with all ones
  - 1514 path with maximum probability
    
    1514 path with maximum probability
  - 1590 make sum divisible by p
    
    1590 make sum divisible by p
- 1600 1699
  1600 1699
  - 1644 lowest common ancestor of a binary tree ii
    
    1644 lowest common ancestor of a binary tree ii
  - 1650 lowest common ancestor of a binary tree iii
    
    1650 lowest common ancestor of a binary tree iii
- 1800 1899
  1800 1899
  - 1804 implement trie ii prefix tree
    
    1804 implement trie ii prefix tree
  - 1854 maximum population year
    
    1854 maximum population year
- 2000 2099
  2000 2099
  - 2050 parallel courses iii
    
    2050 parallel courses iii
  - 2092 find all people with secret
    
    2092 find all people with secret
- 2100 2199
  2100 2199
  - 2127 maximum employees to be invited to a meeting
    
    2127 maximum employees to be invited to a meeting
- 2400 2499
  2400 2499
  - 2421 number of good paths
    
    2421 number of good paths
- 2700 2799
  2700 2799
  - 2788 split strings by separator
    
    2788 split strings by separator
- 2800 2899
  2800 2899
  - 2850 minimum moves to spread stones over grid
    
    2850 minimum moves to spread stones over grid
  - 2851 string transformation
    
    2851 string transformation
  - 2861 maximum number of alloys
    
    2861 maximum number of alloys
- 2900 2999
  2900 2999
  - 2997 minimum number of operations to make array xor equal to k
    
    2997 minimum number of operations to make array xor equal to k
- 3000 3099
  3000 3099
  - 3010 divide an array into subarrays with minimum cost i
    
    3010 divide an array into subarrays with minimum cost i
  - 3011 find if array can be sorted
    
    3011 find if array can be sorted
  - 3012 minimize length of array using operations
    
    3012 minimize length of array using operations
  - 3013 divide an array into subarrays with minimum cost ii
    
    3013 divide an array into subarrays with minimum cost ii
  - 3025 find the number of ways to place people i
    
    3025 find the number of ways to place people i
  - 3026 maximum good subarray sum
    
    3026 maximum good subarray sum
  - 3039 apply operations to make string empty
    
    3039 apply operations to make string empty
  - 3040 maximum number of operations with the same score ii
    
    3040 maximum number of operations with the same score ii
  - 3041 maximize consecutive elements in an array after modification
    
    3041 maximize consecutive elements in an array after modification
  - 3047 find the largest area of square inside two rectangles
    
    3047 find the largest area of square inside two rectangles
  - 3048 earliest second to mark indices i
    
    3048 earliest second to mark indices i
  - 3070 count submatrices with top left element and sum less than k
    
    3070 count submatrices with top left element and sum less than k
  - 3071 minimum operations to write the letter y on a grid
    
    3071 minimum operations to write the letter y on a grid
  - 3072 distribute elements into two arrays ii
    
    3072 distribute elements into two arrays ii
- Topics
  Topics
  - Binary Trees
  - Bit Operations
  - Dynamic Programming
  - Design Questions
  - Graph Theory Graph Theory
    Table of contents
    
    Topological Sort
    
    Breadth-First Search (BFS)
  - Greedy Algorithms
  - Heap (Priority Queue)
  - Linked List
  - Monotonic Queue
  - Monotonic Stack
  - Prefix Sum and Difference
  - Sliding Window
  - Sweep Line Algorithm
  - Prefix Tree
Math
Math
- 01 Prime Numbers
  01 Prime Numbers
- 02 Divisor
  02 Divisor
- 03 Euler Function
  03 Euler Function
- 04 Binary Exponentiation
  04 Binary Exponentiation
- 05 Extended Euclidean
  05 Extended Euclidean
- 06 Chinese Remainder Theorem
  06 Chinese Remainder Theorem
- 07 Gaussian Elimination
  07 Gaussian Elimination
- 08 Combinatorial Number
  08 Combinatorial Number
Miscellaneous
Miscellaneous

Graph Theory⚓︎

Topological Sort⚓︎

210: Course Schedule II: \({\color{yellow}Template}\)
207: Course Schedule
269: Alien Dictionary
936: Stamping The Sequence: \({\color{red}Difficult}\)
851: Loud and Rich
1136: Parallel Courses
2050: Parallel Courses III
2127: Maximum Employees to Be Invited to a Meeting

Breadth-First Search (BFS)⚓︎

1162: As Far from Land as Possible