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
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

Bit Operations⚓︎

268: Missing Number
231: Power of Two
191: Number of 1 Bits
762: Prime Number of Set Bits in Binary Representation
136: Single Number: One number in the array occurs an odd number of times, all other numbers occur an even number of times, return the number that occurs an odd number of times.
137: Single Number II: There is a number in the array that occurs less than \(m\) times, and all other numbers occur \(m\) times, return the number that occurs less than \(m\) times.
260: Single Number III: There are two different numbers in the array that occur an odd number of times, and all other numbers occur an even number of times; return the two numbers that occur an odd number of times.
476: Number Complement
371: Sum of Two Integers
201: Bitwise AND of Numbers Range
2997: Minimum Number of Operations to Make Array XOR Equal to K