geemaple / Leetcode
Licence: mit
LeetCode solutions, written in python and cpp(LeetCode解题报告，记录自己的leetcode成长之路)
Stars: ✭ 179
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《算法技术手册》/ Algorithms in a Nutshell
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《STL源码剖析》/ The Annotated STL Sources
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《算法心得：高效算法的奥秘》/ Hacker's Delight, 2nd Edition
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Leetcode
Math
| Problem | Solution | Time | Space | Difficulty | Note |
|---|---|---|---|---|---|
| 263.ugly-number | cpp, python | O(1) | O(1) | Easy | O(T) = O(LogN), N <= 2^31, O(T) = 32 |
| Problem | Solution | Time | Space | Difficulty | Note | Grade |
|---|---|---|---|---|---|---|
| 002.add-two-numbers | cpp, python | O(N) | O(1) | Medium/S-- | ||
| 007.reverse-integer | cpp, python | O(L) | O(1) | Easy/S-- | ||
| 008.string-to-integer-atoi | cpp, python | O(N) | O(1) | Medium/S-- | Overflow Check | Awesome |
| 009.palindrome-number | python | O(N) | O(1) | Easy | ||
| 012.integer-to-roman | cpp, python | O(N) | Medium | N = length of results | ||
| 013.roman-to-integer | cpp, python | O(N) | Easy | |||
| 043.multiply-strings | cpp, python | O(M*N) | O(M+N) | Medium/S++ | ||
| 048.rotate-image | cpp, python | O(MN) | O(1) | Medium/S++ | ||
| 067.add-binary | cpp, python | O(N) | O(1) | Easy | ||
| 202.happy-number | cpp, python | O(N) | Easy | |||
| 273.integer-to-english-words | python | O(N) | O(N) | Hard | ||
| 311.sparse-matrix-multiplication | cpp, python | O(N^3) | O(N^2) | Medium/S-- | ||
| 326.power-of-three | python | O(1) | O(1) | Easy/S++ | ||
| 342.power-of-four | python | O(1) | O(1) | Easy/S++ | ||
| 415.add-strings | cpp, python | O(N) | O(1) | Easy | ||
| 829.consecutive-numbers-sum | python | O(sqrt(N)) | O(1) | Hard | ||
| 836.rectangle-overlap | cpp, python | O(1) | O(1) | Easy |
Bit
| Problem | Solution | Time | Space | Difficulty | Note | Grade |
|---|---|---|---|---|---|---|
| 136.single-number | cpp, python | O(N) | O(1) | Easy | xor | Perfect |
| 231.power-of-two | python | O(1) | O(1) | Easy | ||
| 318.maximum-product-of-word-lengths | cpp, python | O(N^2) | O(N) | Medium/S++ | mask | Great |
| 393.utf-8-validation | cpp, python | O(N) | O(1) | Medium/S-- | Perfect | |
| 751.ip-to-cidr | python | O(N) | O(1) | Easy/SSS |
Design
| Problem | Solution | Time | Space | Difficulty | Note | Grade |
|---|---|---|---|---|---|---|
| 535.encode-and-decode-tinyurl | python | O(1) | O(N) | Medium |
Array and String
| Problem | Solution | Time | Space | Difficulty | Note |
|---|---|---|---|---|---|
| 038.count-and-say | python | N/A | O(1) | Easy | |
| 169.majority-element | cpp, python | O(N) | O(1) | Easy | Boyer–Moore majority vote algorithm |
| 229.majority-element-ii | cpp, python | O(N) | O(1) | Medium | Boyer–Moore majority vote algorithm |
| Problem | Solution | Time | Space | Difficulty | Note | Grade |
|---|---|---|---|---|---|---|
| 014.longest-common-prefix | cpp, python | O(S) | O(1) | Easy/S-- | Trie | Perfect |
| 031.next-permutation | cpp, python | O(N) | O(1) | Medium | Array | Great |
| 041.first-missing-positive | python | O(N) | O(1) | Hard | ||
| 042.trapping-rain-water | cpp, python | O(N) | O(N) | Hard | Scan Twice | Perfect |
| 054.spiral-matrix | cpp | python | O(N) | O(1) | Medium | |
| 056.merge-intervals | cpp, python | O(N * logN) | O(1) | Medium | Sort | N = number of intervals |
| 057.insert-interval | cpp, python | O(N) | O(1) | Hard | Sort | N = number of intervals |
| 066.plus-one | cpp, python | O(N) | O(1) | Easy | ||
| 068.text-justification | python | O(N) | O(N) | Hard | ||
| 118.pascals-triangle | cpp, python | O(N^2) | O(1) | Easy | Perfect | |
| 119.pascals-triangle-ii | cpp, python | O(N^2) | O(1) | Easy | Perfect | |
| 157.read-n-characters-given-read4 | cpp, python | O(N) | O(1) | Easy | String | |
| 161.one-edit-distance | cpp, python | O(N) | O(1) | Medium | String | Perfect |
| 163.missing-ranges | cpp, python | O(N) | O(1) | Medium | Array | Mind int overflow |
| 215.kth-largest-element-in-an-array | cpp, python | O(N) | O(1) | Medium/S-- | quick-select | best = O(N), worst = O(N^2) |
| 228.summary-ranges | python | O(N) | O(1) | Medium | ||
| 240.search-a-2d-matrix-ii | cpp, python | O(M + N) | O(1) | Medium | ||
| 251.flatten-2d-vector | python | - | O(N) | Medium | ||
| 271.encode-and-decode-strings | cpp, python | O(N) | O(1) | Easy | String | N = count of chars |
| 277.find-the-celebrity | cpp, python | O(N) | O(1) | Medium | ||
| 280.wiggle-sort | python | O(N) | O(1) | Medium | ||
| 289.game-of-life | python | O(MN) | O(1) | Medium | ||
| $324.wiggle-sort-ii | python | O(NLogN) | O(N) | Medium | Follow up | |
| 370.range-addition | cpp, python | O(N + K) | O(1) | Medium | Array | Perfect |
| 388.longest-absolute-file-path | cpp, python | O(N) | O(N) | Medium | String | |
| 408.valid-word-abbreviation | cpp, python | O(N) | O(1) | Easy | ||
| 448.find-all-numbers-disappeared-in-an-array | python | O(N) | O(1) | Easy/SSS | ||
| 463.island-perimeter | python | O(N) | O(1) | Easy/S++ | ||
| 527.word-abbreviation | cpp, python | O(N * L) | O(N) | Hard | L = avg word length | |
| 560.subarray-sum-equals-k | cpp, python | O(N) | O(N) | Medium | Great | |
| 657.robot-return-to-origin | python | O(N) | O(1) | Easy | ||
| 674.longest-continuous-increasing-subsequence | cpp, python | O(N) | O(1) | Easy | Perfect | |
| 755.pour-water | python | O(N^2) | O(1) | Medium/S-- | ||
| 796.rotate-string | cpp, python | O(N) | O(1) | Easy | string | |
| 929.unique-email-addresses | python | O(N) | O(N) | Easy |
| Problem | Solution | Time | Difficulty | Tag | Note |
|---|---|---|---|---|---|
| 350.intersection-of-two-arrays-ii | python | O(N * logN) | Easy | ||
| 485.max-consecutive-ones | cpp | O(N) | Easy | ||
| 498.diagonal-traverse | cpp | O(MN) | Medium | ||
| 561.array-partition-i | cpp | O(N * logN) | Easy | ||
| 724.find-pivot-index | cpp | O(N) | Easy | ||
| 747.largest-number-at-least-twice-of-others | cpp | O(N) | Easy | ||
| 832.flipping-an-image | python | O(N) | O(N) | Easy | |
| 859.buddy-strings | cpp | O(N) | Easy | string |
Two Pointers
| Problem | Solution | Time | Space | Difficulty | Note | Grade |
|---|---|---|---|---|---|---|
| 003.longest-substring-without-repeating-characters | cpp, python | O(N) | O(N) | Medium | ||
| 011.container-with-most-water | python | O(N) | O(1) | Medium | ||
| 015.3sum | cpp, python | O(N^2) | O(1) | Medium/S++ | Awesome | |
| 016.3sum-closest | cpp, python | O(N^2) | O(1) | Medium | Cool | |
| 018.4sum | cpp, python | O(N^3) | O(1) | Medium | Awesome | |
| 019.remove-nth-node-from-end-of-list | cpp, python | O(N) | O(1) | Medium | Perfect | |
| 026.remove-duplicates-from-sorted-array | cpp, python | O(N) | O(1) | Easy | Perfect | |
| 027.remove-element | cpp, python | O(N) | O(1) | Easy | ||
| 028.implement-strstr | cpp, python | O(M + N) | O(1) | Easy | Pattern Searching | KMP |
| 042.trapping-rain-water | cpp, python | O(N) | O(1) | Hard | Two Pointers | |
| 075.sort-colors | cpp python | O(N) | O(1) | Medium | counting-sort | |
| 076.minimum-window-substring | cpp, python | O(N) | O(N) | Hard | ||
| 088.merge-sorted-array | cpp, python | O(N + M) | O(1) | Easy | Perfect | |
| 125.valid-palindrome | cpp, python | O(N) | O(1) | Easy | Perfect | |
| 159.longest-substring-with-at-most-two-distinct-characters | cpp, python | O(N) | O(N) | Hard | ||
| 167.two-sum-ii-input-array-is-sorted | cpp, python | O(N) | O(1) | Easy | Perfect | |
| 209.minimum-size-subarray-sum | cpp, python | O(N) | O(1) | Medium | ||
| 234.palindrome-linked-list | cpp, python | O(N) | O(1) | Easy | maybe Harder | |
| 283.move-zeroes | cpp, python | O(N) | O(1) | Easy | Perfect | |
| 340.longest-substring-with-at-most-k-distinct-characters | cpp, python | O(N) | O(N) | Hard | Cool | |
| 344.reverse-string | cpp, python | O(N) | O(1) | Easy | ||
| 345.reverse-vowels-of-a-string | cpp, python | O(N) | O(1) | Easy | ||
| 350.intersection-of-two-arrays-ii | cpp, python | O(K * logK), k = max(M, N) | O(1) | Easy | hash, binary-search | |
| 532.k-diff-pairs-in-an-array | cpp, python | O(N * logN) | O(1) | Easy | Hash | |
| 844.backspace-string-compare | cpp, python | O(N) | O(1) | Easy | stack |
Linked List
There is actually no algorithm in linked list question, but is really tricky to get one right
| Problem | Solution | Time | Space | Difficulty | Grade | Note |
|---|---|---|---|---|---|---|
| 021.merge-two-sorted-lists | cpp, python | O(N) | O(1) | Easy | Perfect | |
| 024.swap-nodes-in-pairs | cpp, python | O(N) | O(1) | Medium | Great | |
| 025.reverse-nodes-in-k-group | cpp, python | O(N) | O(1) | Hard/S-- | Perfect | |
| 086.partition-list | cpp, python | O(N) | O(1) | Medium | Perfect | |
| 092.reverse-linked-list-ii | cpp, python | O(N) | O(1) | Medium | Perfect | |
| 141.linked-list-cycle | cpp, python | O(N) | O(1) | Easy | perfect | |
| 142.linked-list-cycle-ii | cpp, python | O(N) | O(1) | Medium/S++ | Perfect | |
| 160.intersection-of-two-linked-lists | cpp, python | O(N + M) | Easy | Perfect | two-pointers | |
| 206.reverse-linked-list | cpp, python | O(N) | O(1) | Easy/S++ | Perfect |
| Problem | Solution | Time | Difficulty | Tag | Note |
|---|---|---|---|---|---|
| 61.rotate-list | python | O(N) | Medium | ||
| 143.reorder-list | python | O(N) | Medium | ||
| 138.copy-list-with-random-pointer | python | O(N) | Medium | ||
| 148.sort-list | python | O(N * logN) | Medium | ||
| 203.remove-linked-list-elements | python | O(N) | Easy | ||
| 237.delete-node-in-a-linked-list | python | O(1) | Easy | ||
| 328.odd-even-linked-list | python | O(N) | Medium |
Binary Search
| Problem | Solution | Time | Space | Difficulty | Note |
|---|---|---|---|---|---|
| 004.median-of-two-sorted-arrays | cpp, python | O(log(N)) | O(1) | TODO: find kth solution | |
| 278.first-bad-version | cpp, python | O(logN) | O(1) | Easy | 3 template |
| 658.find-k-closest-elements | cpp, python | Log(N - K) | O(1) | Medium | |
| 704.binary-search | cpp, python | O(logN) | O(1) | Easy | TODO: missing one template |
| 1150.check-if-a-number-is-majority-element-in-a-sorted-array.cpp | cpp, python | O(logN) | O(1) | Easy |
| Problem | Solution | Time | Space | Difficulty | Statistic | Note |
|---|---|---|---|---|---|---|
| 029.divide-two-integers | cpp, python | O(logN) | O(1) | Medium/S++ | Math | |
| $033.search-in-rotated-sorted-array | cpp, python | O(logN) | O(1) | Medium/S++ | Perfect | |
| 034.find-first-and-last-position-of-element-in-sorted-array | cpp, python | O(LogN) | O(1) | Medium | Perfect | |
| 050.powx-n | cpp, python | O(logN) | O(1) | Medium/S++ | ||
| $069.sqrtx | cpp, python | O(logN) | O(1) | Easy | Perfect | |
| 074.search-a-2d-matrix | cpp, python | O(logN) | O(1) | Medium | N = row * col | |
| 081.search-in-rotated-sorted-array-ii | cpp, python | O(logN) ~ O(N) | O(1) | Medium/S++ | ||
| 153.find-minimum-in-rotated-sorted-array | cpp, python | O(logN) | O(1) | Medium | Perfect | |
| 154.find-minimum-in-rotated-sorted-array-ii | cpp, python | O(logN) ~ O(N) | O(1) | Hard | ||
| 162.find-peak-element | cpp, python | O(logN) | O(1) | Medium | Perfect | |
| 270.closest-binary-search-tree-value | cpp, python | O(LogN) | O(1) | Easy | Perfect | |
| 302.smallest-rectangle-enclosing-black-pixels | cpp, python | O(MLogN + NLogM) | O(1) | Hard/SSS | Perfect | |
| 367.valid-perfect-square | cpp, python | O(LogN) | O(1) | Easy | Perfect | |
| 374.guess-number-higher-or-lower | cpp, python | O(LogN) | O(1) | Easy | Perfect | |
| 702.search-in-a-sorted-array-of-unknown-size | cpp, python | O(LogN) | O(1) | Medium | Perfect | |
| 852.peak-index-in-a-mountain-array | cpp, python | O(logN) | O(1) | Easy | Golden-section search | |
| 1150.check-if-a-number-is-majority-element-in-a-sorted-array.cpp | cpp, python | O(logN) | O(1) | Easy |
Divide and Conquer
| Problem | Solution | Time | Space | Difficulty | Note |
|---|---|---|---|---|---|
| 098.validate-binary-search-tree | cpp, python | O(N) | O(1) | Medium | |
| 236.lowest-common-ancestor-of-a-binary-tree | cpp, python | O(N) | O(1) | Medium |
| Problem | Solution | Time | Space | Difficulty | Note | Grade |
|---|---|---|---|---|---|---|
| 104.maximum-depth-of-binary-tree | cpp, python | O(N) | O(1) | Easy | Perfect | |
| 110.balanced-binary-tree | cpp, python | O(N) | O(1) | Easy | Perfect | |
| 273.integer-to-english-words | python | O(N) | O(N) | Hard | ||
| 282.expression-add-operators | cpp, python | O(2 ^ N) | O(N) | Hard/SSS | DFS | N = length of input |
| 687.longest-univalue-path | cpp, python | O(N) | O(1) | Easy/S++ | Perfect |
Tree Traversal
| Problem | Solution | Time | Space | Difficulty | Note | Grade |
|---|---|---|---|---|---|---|
| 94.binary-tree-inorder-traversal | cpp, python | O(N) | O(1) | Medium/S++ | Perfect | |
| 102.binary-tree-level-order-traversal | cpp, python | O(N) | O(H) | Medium | Perfect | |
| 103.binary-tree-zigzag-level-order-traversal | cpp, python | O(N) | O(N) | Medium | Perfect | |
| 107.binary-tree-level-order-traversal-ii | cpp, python | O(N) | O(N) | Easy | Perfect | |
| 114.flatten-binary-tree-to-linked-list | cpp, python | O(N) | O(1) | Medium | Cool | |
| 130.surrounded-regions | cpp, python | O(MN) | O(M & N) | Medium | BFS | |
| 144.binary-tree-preorder-traversal | cpp, python | O(N) | O(1) | Medium/S-- | Perfect | |
| 145.binary-tree-postorder-traversal | cpp, python | O(N) | O(1) | Hard/SSS | Perfect | |
| 156.binary-tree-upside-down | cpp, python | O(V) | O(1) | Medium | ||
| 173.binary-search-tree-iterator | cpp, python | O(1) | O(H) | Medium/S-- | Perfect | |
| 257.binary-tree-paths | cpp, python | O(N) | O(1) | Easy | Perfect | |
| 285.inorder-successor-in-bst | cpp, python | O(H) | O(1) | Medium | BST | H = height of the tree |
| 286.walls-and-gates | cpp, python | O(MN) | O(MN) | Medium | BFS | |
| 297.serialize-and-deserialize-binary-tree | cpp, python | O(N) | O(N) | Hard | Cool | |
| 314.binary-tree-vertical-order-traversal | cpp, python | O(V) | O(V) | Medium | ||
| 366.find-leaves-of-binary-tree | cpp, python | O(V) | O(V) | Medium | ||
| 426.convert-binary-search-tree-to-sorted-doubly-linked-list | cpp, python | O(N) | O(1) | Medium | Perfect | |
| 538.convert-bst-to-greater-tree | cpp, python | O(V) | O(1) | Easy |
Graph Traversal
| Problem | Solution | Time | Space | Difficulty | Note | Grade |
|---|---|---|---|---|---|---|
| 127.word-ladder | cpp, python | O(N^2 * L^2) | O(N) | Medium/S++ | BFS | Bad |
| 133.clone-graph | cpp, python | O(V + E) | O(N) | Medium | Great | |
| 200.number-of-islands | cpp, python | O(MN) | O(MN) | Medium | BFS/DFS | union-find |
| 207.course-schedule | cpp, python | O(V + E) | O(V + E) | Medium | Perfect | |
| 210.course-schedule-ii | cpp, python | O(V + E) | O(V) | Medium | topological-sort | Awesome |
| 269.alien-dictionary | python | O(V + E) | O(V + E) | Hard | ||
| 323.number-of-connected-components-in-an-undirected-graph | cpp, python | O(V+E) | O(V+E) | Medium | union-find | Bad |
| 433.minimum-genetic-mutation | cpp, python | O(V + E) | O(N) | Medium | ||
| 444.sequence-reconstruction | cpp, python | O(V+E) | O(V) | Medium | topological-sort | |
| 773.sliding-puzzle | python | O(V + E) | O(N) | Hard/SSS | ||
| 815.bus-routes | python | O(V + E) | O(N) | Hard/SSS |
Backtracking
| Problem | Solution | Time | Space | Difficulty | Note |
|---|---|---|---|---|---|
| 037.sudoku-solver | python | O(2 ^ N) | O(N) | Medium | N = black count |
| Problem | Solution | Time | Space | Difficulty | Tag | Note |
|---|---|---|---|---|---|---|
| 017.letter-combinations-of-a-phone-number | cpp, python | O(2 ^ N) | O(N) | Medium | ||
| 022.generate-parentheses | python | O(ans) | O(N) | Medium | ||
| 039.combination-sum | cpp, python | O(N^K), k=target/min | O(K) | Medium | DFS | Perfect |
| 040.combination-sum-ii | cpp, python | O(2^K), k=target/min | O(K) | Medium/S-- | DFS | Perfect |
| 046.permutations | cpp, python | O(N * N!) | O(N) | Medium | DFS | Perfect |
| 047.permutations-ii | cpp, python | O(N * N!) | O(N) | Medium/S++ | DFS | Perfect |
| 051.n-queens | cpp, python | O(N^N) | O(N) | Hard | DFS | Awesome |
| 052.n-queens-ii | cpp, python | O(N^N) | O(N) | Hard | DFS | Perfect |
| 078.subsets | cpp, python | O(N * 2^N) | O(N) | Medium | DFS/Iteration/Bit | |
| 079.word-search | cpp, python | O(MN * L^2), L = length of words | O(MN) | Medium | DFS | |
| 090.subsets-ii | cpp, python | O(N * 2^N) | O(N) | Medium(S++) | DFS/Iteration | |
| 126.word-ladder-ii | cpp, python | - | O(N) | Hard/SSS | DFS Pruning | Awesome |
| 131.palindrome-partitioning | cpp, python | O(2^N) | O(N) | Medium | DFS | Perfect |
Hash Table
| Problem | Solution | Time | Space | Difficulty | Note |
|---|---|---|---|---|---|
| 036.valid-sudoku | cpp, python | O(N ^ 2) | O(N ^ 2) | Medium | array-indexes |
| Problem | Solution | Time | Space | Difficulty | Grade | Note |
|---|---|---|---|---|---|---|
| 001.two-sum | cpp, python | O(N) | O(N) | Easy | Perfect | |
| 030.substring-with-concatenation-of-all-words | cpp, python | O(MN) | O(M) | Hard/SSS | Cool | TODO O(N) |
| 49.group-anagrams | cpp | O(N * k * Logk) | Medium | |||
| 170.two-sum-iii-data-structure-design | cpp, python | O(N) | O(N) | Easy | Awesome | |
| 202.happy-number | cpp, python | O(N) | Easy | |||
| 217.contains-duplicate | cpp | O(N) | Easy | |||
| 219.contains-duplicate-ii | cpp | O(N) | Easy | |||
| 242.valid-anagram | cpp, python | O(N) | O(1) | Easy | Perfect | |
| 249.group-shifted-strings | cpp | O(N * K) | Medium | |||
| 347.top-k-frequent-elements | cpp | O(N * LogN) | Medium | TODO: quick-sort, bucket-sort | ||
| 350.intersection-of-two-arrays-ii | cpp | O(MN) | Easy | |||
| 359.logger-rate-limiter | cpp | O(1) | Easy | amortized | ||
| 380.insert-delete-getrandom-o1 | cpp | O(1) | Medium | |||
| 447.number-of-boomerangs | cpp, python | O(N^2) | O(N) | Easy | Cool | |
| 454.4sum-ii | cpp | O(N ^ 2) | Medium | |||
| 599.minimum-index-sum-of-two-lists | cpp | O(M + N) | Easy | |||
| 652.find-duplicate-subtrees | cpp | O(N) | Medium | |||
| 760.find-anagram-mappings | python | O(N) | O(N) | Easy | ||
| 771.jewels-and-stones | cpp | O(M + N) | Easy |
| Problem | Solution | Time | Space | Difficulty | Note | Grade |
|---|---|---|---|---|---|---|
| 128.longest-consecutive-sequence | cpp, python | O(N) | O(N) | Hard/S++ | Union-find | |
| 205.isomorphic-strings | cpp, python | O(N) | O(N) | Easy | ||
| 246.strobogrammatic-number | cpp, python | O(N) | O(1) | Easy | ||
| 288.unique-word-abbreviation | cpp, python | O(1) | O(N) | Medium | ||
| 349.intersection-of-two-arrays | cpp, python | O(K * logK), k = max(M, N) | O(1) | Easy | two-pointers, binary-search | perfect |
| 387.first-unique-character-in-a-string | cpp, python | O(N) | O(N) | Easy | ||
| 438.find-all-anagrams-in-a-string | cpp, python | O(N) | O(N) | Easy |
queue
| Problem | Solution | Time | Space | Difficulty | Grade | Node |
|---|---|---|---|---|---|---|
| 239.sliding-window-maximum | cpp, python | O(N) | O(N) | Hard | Great | |
| 346.moving-average-from-data-stream | cpp, python | O(1) | O(N) | Easy | Perfect | |
| 933.number-of-recent-calls | cpp, python | O(Inputs) | O(1) | Easy | Perfect | Fast I/O for Competitive Programming |
Heap
| Problem | Solution | Time | Space | Difficulty | Note | Grade |
|---|---|---|---|---|---|---|
| $023.merge-k-sorted-lists | cpp, python | O(N * LogK) | O(K) | Hard | Perfect | |
| 295.find-median-from-data-stream | cpp, python | O(NLogN) | O(N) | Medium | Cool | |
| 378.kth-smallest-element-in-a-sorted-matrix | cpp, python | O((K + M) * LogM) | O(M) | Medium | TODO: binary-search, O(N) solution | |
| 407.trapping-rain-water-ii | cpp, python | O(M * N * Log(M + N)) | O(M + N) | Hard/SSS | Bad |
Stack
| Problem | Solution | Time | Space | Difficulty | Note | Grade |
|---|---|---|---|---|---|---|
| 020.valid-parentheses | cpp, python | O(N) | O(N) | Easy | Perfect | |
| 084.largest-rectangle-in-histogram | cpp, python | O(N) | O(N) | Hard/S++ | Perfect | |
| 085.maximal-rectangle | cpp, python | O(MN) | O(N) | Hard/SSS | Perfect | |
| 155.min-stack | cpp, python | O(1) | O(N) | Easy/S-- | Cool | |
| 341.flatten-nested-list-iterator | python | - | O(N) | Medium/S++ | ||
| 394.decode-string | cpp, python | O(N) | O(N) | Medium | Perfect | |
| 654.maximum-binary-tree | cpp, python | O(N) | O(N) | Hard/SSS | Perfect | |
| 739.daily-temperatures | python | O(N) | O(N) | Medium |
Sweep Line
| Problem | Solution | Time | Space | Difficulty | Note | Grade |
|---|---|---|---|---|---|---|
| $253.meeting-rooms-ii | cpp, python | O(NlogN) | O(N) | Medium | Perfect |
Dynamic Programming
| Problem | Solution | Time | Space | Difficulty | Note | Grade |
|---|---|---|---|---|---|---|
| 005.longest-palindromic-substring | python | O(N^2) | O(1) | Medium | ||
| 010.regular-expression-matching | cpp, python | O(MN) | O(MN) | Hard/S++ | Sequence | |
| 044.wildcard-matching | cpp, python | O(MN) | O(MN) | Hard | Sequence | |
| 053.maximum-subarray | cpp, python | O(N) | O(1) | Easy | Perfect | |
| 062.unique-paths | cpp, python | O(MN) | O(MN) | Medium | Coordinates | |
| 063.unique-paths-ii | cpp, python | O(MN) | O(MN) | Medium | Coordinates | |
| 064.minimum-path-sum | cpp, python | O(MN) | O(MN) | Medium | Coordinates | |
| 070.climbing-stairs | cpp, python | O(N) | O(1) | Easy | Coordinates | Perfect |
| 072.edit-distance | cpp, python | O(MN) | O(N) | Hard/S-- | Sequence | |
| 087.scramble-string | cpp, python | O(N^4) | O(N^3) | Hard/SSS | Range | |
| 091.decode-ways | cpp, python | O(N) | O(N) | Medium/S++ | Partition | |
| 097.interleaving-string | cpp, python | O(MN) | O(MN) | Hard/S-- | Sequence | |
| 115.distinct-subsequences | cpp, python | O(MN) | O(MN) | Hard/S-- | Sequence | |
| 120.triangle | cpp, python | O(N^2) | O(N) | Medium | Coordinates | Perfect |
| 132.palindrome-partitioning-ii | cpp, python | O(N^2) | O(N^2) | Hard | Partition | |
| 188.best-time-to-buy-and-sell-stock-iv | cpp, python | O(N*K) | O(N * K) | Hard/SSS | ||
| 198.house-robber | cpp, python | O(N) | O(1) | Easy | Sequence | Perfect |
| 121.best-time-to-buy-and-sell-stock | cpp, python | O(N) | O(1) | Easy | Coordinates | |
| 123.best-time-to-buy-and-sell-stock-iii | cpp, python | O(N) | O(N) | Hard/SSS | ||
| 213.house-robber-ii | cpp, python | O(N) | O(1) | Medium/S-- | Sequence | Perfect |
| 221.maximal-square | cpp, python | O(MN) | O(N) | Medium/S-- | Coordinates | Perfect |
| 256.paint-house | cpp, python | O(N) | O(N) | Easy/S-- | Sequence | |
| 265.paint-house-ii | cpp, python | O(MN) | O(MN) | Hard | Sequence | |
| 276.paint-fence | cpp, python | O(N) | O(1) | Easy/SSS | Perfect | |
| 279.perfect-squares | cpp, python | O(N ^ 1.5) | O(N) | Medium | Partition | |
| 300.longest-increasing-subsequence | cpp, python | O(NlogN) | O(N) | Medium/SSS | Binary-search / DP | Perfect |
| 312.burst-balloons | cpp, python | O(N^3) | O(N^2) | Hard/S-- | Range | |
| 322.coin-change | cpp, python | O(L*N) | O(N) | Medium | N = amount, L = len(coins) | |
| 338.counting-bits | cpp, python | O(N) | O(1) | Medium/S-- | Bit-manipulation | |
| 354.russian-doll-envelopes | cpp, python | O(N*logN) | O(N) | Hard/S-- | Coordinates | |
| $361.bomb-enemy | cpp, python | O(MN) | O(MN) | Medium/S++ | Coordinates | |
| $368.largest-divisible-subset | cpp, python | O(N^2) | O(N) | Medium/S++ | Coordinates | Awesome |
| 377.combination-sum-iv | cpp, python | O(M*N) | O(N) | Medium | Backpack | |
| 474.ones-and-zeroes | cpp, python | O(LMN) | O(LMN) | Medium | Sequence | |
| 516.longest-palindromic-subsequence | cpp, python | O(N^2) | O(N^2) | Medium | ||
| 787.cheapest-flights-within-k-stops | python | O(K * E) | O(N) | Hard/SSS |
Red Black Tree
Since python got no built-in AVL data-structure, these questions written in python may perform worse
| Problem | Solution | Time | Space | Difficulty | Note | Grade |
|---|---|---|---|---|---|---|
| $683.k-empty-slots | cpp, python | O(NLogN) | O(N) | Hard/SSS | Min Queue | Bad |
Greedy
| Problem | Solution | Time | Space | Difficulty | Tag | Note |
|---|---|---|---|---|---|---|
| 45.jump-game-ii | cpp, python | O(N) | O(1) | Hard | ||
| 055.jump-game | cpp, python | O(N) | O(1) | Medium | dynamic-programming | |
| 122.best-time-to-buy-and-sell-stock-ii | cpp, python | O(N) | O(1) | Easy | ||
| $406.queue-reconstruction-by-height | cpp, python | O(N^2) | O(1) | Medium/S++ | Sort Multiple Keys |
Union Find
| Problem | Solution | Time | Space | Difficulty | Note | Grade |
|---|---|---|---|---|---|---|
| 261.graph-valid-tree | cpp, python | O(E) | O(N) | Medium | BFS/DFS | Perfect |
| 305.number-of-islands-ii | cpp, python | O(N) | O(MN) | Hard | N = len(positions) | |
| 721.accounts-merge | cpp, python | O(MN) | O(MN) | Medium | ||
| 924.minimize-malware-spread | python | O(N^2) | O(N) | Hard | TODO | Bad |
Trie
| Problem | Solution | Time | Space | Difficulty | Tag | Note |
|---|---|---|---|---|---|---|
| 208.implement-trie-prefix-tree | cpp, python | O(L) | O(N * L) | Medium | - | L = len(word), N = number of words |
| 211.add-and-search-word-data-structure-design | cpp, python | add = O(L), find >= O(L) | O(N * L) | Medium/S-- | DFS | L = len(word), N = count(words) |
| 212.word-search-ii | cpp, python | O(M * N * L * L) | MAX(O(MN), O(K * L)) | Hard | DFS | K = number of words, L = avg length of words |
| 336.palindrome-pairs | python | O(N * L^2) | O(N) | Hard/SSS | ||
| 425.word-squares | cpp, python | O(-) | O(NL) | Hard/SSS | DFS Pruning | |
| 677.map-sum-pairs | cpp, python | O(L), O(KL) | O(N * L) | Medium | L = length of input, k = number of items found |
Other
| Problem | Solution | Difficulty | Tag | Note |
|---|---|---|---|---|
| 175.combine-two-tables | sql | Easy | SQL |
Lintcode
Below are Lintcode questions that worth trying
| Problem | Solution | Time | Space | Difficulty | Tag | Note |
|---|---|---|---|---|---|---|
| 039.recover-rotated-sorted-array | cpp, python | O(N) | O(1) | Easy/S++ | Binary-search, Two-pointers | |
| 077.longest-common-subsequence | cpp, python | O(M*N) | O(M*N) | Medium | dynamic-programming | |
| 081.find-median-from-data-stream | cpp, python | O(N * LogN) | O(N) | Hard | Heap | |
| 089.k-sum | cpp, python | O(NKT) | O(NKT) | Hard | dynamic-programming | |
| 091.minimum-adjustment-cost | cpp, python | O((100^2)N) | O(100N) | Medium | dynamic-programming | |
| 092.backpack | cpp, python | O(M*N) | O(M) | Medium | dynamic-programming | |
| 125.backpack-ii | cpp, python | O(M*N) | O(M) | Medium/S++ | dynamic-programming | |
| 139.subarray-sum-closest | cpp, python | O(NlogN) | O(N) | Medium | Subarray | |
| 144.interleaving-positive-and-negative-numbers | cpp, python | O(N) | O(1) | Medium | two-pointers | |
| 183.wood-cut | cpp, python | O(N * LogN) | O(1) | Medium/S-- | binary-search | |
| 382.triangle-count | cpp, python | O(N^2) | O(1) | Medium | two-pointers | |
| 390.find-peak-element-ii | cpp, python | O(M + N) | O(1) | Hard/SSS | binary-search | |
| 391.number-of-airplanes-in-the-sky | cpp, python | O(NlogN) | O(N) | Medium | sweep-line | |
| 394.coins-in-a-line | cpp, python | O(N) | O(N) | Medium | dynamic-programming | |
| 396.coins-in-a-line-iii | cpp, python | O(N^2) | O(N^2) | Hard/SSS | dynamic-programming | |
| 437.copy-books | cpp, python | O(K * N^2) / O(N * LogA) | O(NK) | Hard/SSS | dynamic-programming / binary-search | |
| 440.backpack-iii | cpp, python | O(MN) | O(M) | Hard/SSS | dynamic-programming | |
| 447.search-in-a-big-sorted-array | cpp, python | O(LogK) | O(1) | binary-search | Medium/S++ | |
| 465.kth-smallest-sum-in-two-sorted-arrays | cpp, python | O((K + N) * LogN) | O(N) | Hard | heap | N = B.size() |
| 543.kth-largest-in-n-arrays | cpp, python | O(M * N * LogK) | O(K) | Easy | heap | |
| 526.load-balancer | cpp, python | O(1) | O(N) | Medium | Hash + Array | |
| 563.backpack-v | cpp, python | O(M*N) | O(M) | Medium | dynamic-programming | |
| 586.sqrtx-ii | cpp, python | O(logN) | O(N) | Medium | binary-search | |
| 589.connecting-graph | cpp, python | O(1) | O(N) | Medium | union-find | |
| 590.connecting-graph-ii | cpp, python | O(1) | O(N) | Medium | union-find | |
| 591.connecting-graph-iii | cpp, python | O(1) | O(N) | Medium | union-find | |
| 598.zombie-in-matrix | cpp, python | O(MN) | O(MN) | Medium | graph-traversal | |
| 611.knight-shortest-path | cpp, python | O(MN) | O(MN) | Medium | graph-traversal | |
| 618.search-graph-nodes | cpp, python | O(V + E) | O(V) | Medium | tree-traversal | |
| 629.minimum-spanning-tree | cpp, python | O(N * logN) | O(N) | Hard | union-find | Prim, Kruskal |
| 652.factorization | cpp, python | O(N) | O(LogN) | Medium/S++ | N = input number |
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