leetcode/

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leetcode

Problems list.

• leetcode
  • important
  • data structures
    • linked list
    • stack
    • tree
    • graph
    • heap
  • maths
  • dp
  • string
  • bitwise
  • divide and conquer
  • depth-first search (dfs)
  • misc

important

• 0023_merge-k-sorted-lists
  • HARD: linked list, min-heap
• 0033_search-in-rotated-sorted-array
  • binary search
• 0034_find-first-and-last-position-of-element-in-sorted-array
  • binary search
• 0053_maximum-subarray
  • dp, divide and conquer
• 0096_unique-binary-search-trees
  • BST, maths
• 0137_single-number-ii
  • bitwise
• 0142_linked-list-cycle-ii
  • linked list, Floyd's Tortoise and Hare, loop detection
• 0148_sort-list
  • linked list, merge sort, divide and conquer
• 0169_majority-element
  • hashmap, divide and conquer, voting, randomized, partial sorting ...
• 0222_count-complete-tree-nodes
  • binary tree, post-order traversal
• 0230_kth-smallest-element-in-a-bst
  • BST, in-order traversal
• 0260_single-number-iii
  • bitwise
• 0279_perfect-squares
  • dp, maths
• 0287_find-the-duplicate-number
  • Floyd's Tortoise and Hare, loop detection
• 0300_longest-increasing-subsequence
  • dp, binary search
• 0435_non-overlapping-intervals
  • dp, greedy
• 0441_arranging-coins
  • solving quadratic equation in one unknown
• 0450_delete-node-in-a-bst
  • delete a node in a BST, with complex if-else statements
• 0518_coin-change-2
  • dp
• 0525_contiguous-array
  • "coloring the balloons"
• 0572_subtree-of-another-tree
  • tree, preorder-traversal, preprocessing
• 0621_task-scheduler
  • greedy
• 0704_binary-search
  • CLASSIC binary search
• 0912_sort-an-array
  • various kinds of sorting
• 0918_maximum-sum-circular-subarray
  • dp
• 1202_smallest-string-with-swaps
  • dfs, union-find
  • TODO: perfomance issue with maps in golang, need a tool to tack the cost of each call.
• 1218_longest-arithmetic-subsequence-of-given-difference
  • dp

data structures

linked list

• 0002_add-two-numbers
• 0021_merge-two-sorted-lists
• 0024_swap-nodes-in-pairs
• 0141_linked-list-cycle
• 0146_lru-cache: double linked list with map
• 0147_insertion-sort-list
• 0203_remove-linked-list-elements
• 0206_reverse-linked-list
• 0237_delete-node-in-a-linked-list
• 0328_odd-even-linked-list
• 0430_flatten-a-multilevel-doubly-linked-list
• 0445_add-two-numbers-ii
• 0707_design-linked-list
• 0876_middle-of-the-linked-list
• 1429_first-unique-number: double linked list with map

stack

• 0020_valid-parentheses
• 0155_min-stack
• 0901_online-stock-span

tree

• 0096_binary-tree-inorder-traversal
• 0098_validate-binary-search-tree
• 0099_recover-binary-search-tree: HARD(?), BST, in-order traversal
• 0100_same-tree
• 0101_symmetric-tree
• 0102_binary-tree-level-order-traversal
• 0104_maximum-depth-of-binary-tree
• 0107_binary-tree-level-order-traversal-ii
• 0108_convert-sorted-array-to-binary-search-tree
• 0110_balanced-binary-tree
• 0111_minimum-depth-of-binary-tree
• 0112_path-sum
• 0113_path-sum-ii
• 0124_binary-tree-maximum-path-sum: HARD
• 0129_sum-root-to-leaf-numbers
• 0144_binary-tree-preorder-traversal
• 0145_binary-tree-postorder-traversal
• 0208_implement-trie-prefix-tree
• 0226_invert-binary-tree
• 0235_lowest-common-ancestor-of-a-binary-search-tree
• 0236_lowest-common-ancestor-of-a-binary-tree
• 0257_binary-tree-paths
• 0270_closest-binary-search-tree-value
• 0297_serialize-and-deserialize-binary-tree: HARD(?)
• 0315_count-of-smaller-numbers-after-self: HARD, BST
• 0337_house-robber-iii
• 0429_n-ary-tree-level-order-traversal
• 0437_path-sum-iii
• 0449_serialize-and-deserialize-bst
• 0501_find-mode-in-binary-search-tree
• 0508_most-frequent-subtree-sum
• 0530_minimum-absolute-difference-in-bst
• 0543_diameter-of-binary-tree
• 0589_n-ary-tree-preorder-traversal
• 0617_merge-two-binary-trees
• 0662_maximum-width-of-binary-tree
• 0669_trim-a-binary-search-tree
• 0687_longest-univalue-path
• 0700_search-in-a-binary-search-tree
• 0701_insert-into-a-binary-search-tree
• 0814_binary-tree-pruning
• 0872_leaf-similar-trees
• 0965_univalued-binary-tree
• 0968_binary-tree-cameras: HARD, post-order traversal, dp
• 0987_vertical-order-traversal-of-a-binary-tree
• 0993_cousins-in-binary-tree
• 1008_construct-binary-search-tree-from-preorder-traversal
• 1214_two-sum-bsts
• 1302_deepest-leaves-sum
• 1325_delete-leaves-with-a-given-value
• 1430_check-if-a-string-is-a-valid-sequence-from-root-to-leaves-path-in-a-binary-tree

graph

• 0133_clone-graph
• 0138_copy-list-with-random-pointer
• 0207_course-schedule: dfs/bfs, topological sort
• 0210_course-schedule-ii: dfs/bfs, topological sort
• 0802_find-eventual-safe-states: dfs, iterative dfs
• 0886_possible-bipartition: basic dfs in graph

heap

• 1046_last-stone-weight

maths

• 0070_climbing-stairs
• 0258_add-digits
• 0342_power-of-four
• 0367_valid-perfect-square: Newton's Method
• 0528_random-pick-with-weight
• 0829_consecutive-numbers-sum
• 0976_largest-perimeter-triangle
• 1232_check-if-it-is-a-straight-line: gcd

dp

• 0055_jump-game
• 0062_unique-paths
• 0064_minimum-path-sum
• 0072_edit-distance: HARD
• 0264_ugly-number-ii
• 0368_largest-divisible-subset
• 0673_number-of-longest-increasing-subsequence
• 0678_valid-parenthesis-string
• 0712_minimum-ascii-delete-sum-for-two-strings
• 0746_min-cost-climbing-stairs
• 1035_uncrossed-lines
• 1048_longest-string-chain: 0300-like dp with string ops.
• 1143_longest-common-subsequence

string

• 0560_subarray-sum-equals-k

bitwise

• 0190_reverse-bits
• 0201_bitwise-and-of-numbers-range
• 0231_power-of-two
• 0338_counting-bits
• 0461_hamming-distance: turning right most 1
• 0476_number-complement
• 0957_prison-cells-after-n-days: preprocess

divide and conquer

• 0091_decode-ways: recursive solution with memorization
• 0153_find-minimum-in-rotated-sorted-array
• 0154_find-minimum-in-rotated-sorted-array-ii
• 0973_k-closest-points-to-origin

depth-first search (dfs)

• 0130_surrounded-regions: flood fill
• 0547_friend-circles: dfs
• 0695_max-area-of-island: dfs / flood fill
• 0733_flood-fill
• 0827_making-a-large-island: HARD(?) dfs / flood fill
• 0841_keys-and-rooms
• 0994_rotting-oranges: flood fill
• 1162_as-far-from-land-as-possible: flood fill

misc

• 0003_longest-substring-without-repeating-characters
• 0005_longest-palindromic-substring
• 0006_zigzag-conversion
• 0013_3sum
• 0035_search-insert-position: binary search
• 0042_trapping-rain-water: HARD(?)
• 0049_group-anagrams
• 0056_merge-intervals
• 0066_plus-one
• 0067_add-binary
• 0075_sort-colors
• 0121_best-time-to-buy-and-sell-stock
• 0122_best-time-to-buy-and-sell-stock-ii
• 0125_valid-palindrome
• 0151_reverse-words-in-a-string
• 0171_excel-sheet-column-number
• 0200_number-of-islands
• 0202_happy-number
• 0221_maximal-square
• 0238_product-of-array-except-self
• 0274_h-index
• 0275_h-index-ii
• 0278_first-bad-version: binary search
• 0283_move-zeroes
• 0303_range-sum-query-immutable: prefix sum
• 0344_reverse-string
• 0359_logger-rate-limiter
• 0380_insert-delete-getrandom-o1: array with map
• 0383_ransom-note
• 0387_first-unique-character-in-a-string
• 0392_is-subsequence
• 0402_remove-k-digits: greedy
• 0406_queue-reconstruction-by-height: greedy
• 0412_fizz-buzz
• 0438_find-all-anagrams-in-a-string
• 0442_find-all-duplicates-in-an-array
• 0451_sort-characters-by-frequency
• 0463_island-perimeter
• 0468_validate-ip-address: unreal problem, wrong testcases
• 0520_detect-capital
• 0540_single-element-in-a-sorted-array
• 0567_permutation-in-string
• 0763_partition-labels
• 0771_jewels-and-stones
• 0844_backspace-string-compare
• 0937_reorder-data-in-log-files
• 0953_verifying-an-alien-dictionary
• 0986_interval-list-intersections
• 0997_find-the-town-judge
• 1029_two-city-scheduling: greedy?
• 1137_n-th-tribonacci-number
• 1277_count-square-submatrices-with-all-ones
• 1286_iterator-for-combination
• 1426_counting-elements
• 1427_perform-string-shifts
• 1428_leftmost-column-with-at-least-a-one
• 1529_bulb-switcher-iv: greedy?
• 1572_matrix-diagonal-sum