vault backup: 2026-05-30 16:02:33

leetcode/note/medium/128_longest_consecutive_sequence.md

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+---
+id: 128
+title: Longest Consecutive Sequence
+difficulty: Medium
+tags:
+  - array
+  - hash-table
+  - union-find
+status: unsolve
+date_solved: 2026-05-26
+leetcode_url: https://leetcode.com/problems/longest-consecutive-sequence/
+review_needed: false
+---

leetcode/note/medium/2017_grid_game.md

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+---
+id: 2017
+title: Grid Game
+difficulty: Medium
+tags:
+  - array
+  - matrix
+  - prefix-sum
+status: unsolve
+date_solved: 2026-05-26
+leetcode_url: https://leetcode.com/problems/grid-game/
+review_needed: false
+---

leetcode/note/medium/238_product_of_array_except_self.md

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+---
+id: 238
+title: Product of Array Except Self
+difficulty: Medium
+tags:
+  - array
+  - prefix-sum
+status: unsolve
+date_solved: 2026-05-26
+leetcode_url: https://leetcode.com/problems/product-of-array-except-self/
+review_needed: false
+---

leetcode/note/medium/271_encode_and_decode_strings.md

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+---
+id: 271
+title: Encode and Decode Strings
+difficulty: Medium
+tags:
+  - array
+  - hash-table
+  - string
+  - design
+status: unsolve
+date_solved: 2026-05-26
+leetcode_url: https://leetcode.com/problems/encode-and-decode-strings/
+review_needed: false
+---

leetcode/note/medium/347_top_k_frequent_elements.md

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+---
+id: 347
+title: Top K Frequent Elements
+difficulty: Medium
+tags:
+  - array
+  - hash-table
+  - divide-and-conquer
+  - sorting
+  - heap-priority-queue
+  - bucket-sort
+  - quickselect
+status: unsolve
+date_solved: 2026-05-26
+leetcode_url: https://leetcode.com/problems/top-k-frequent-elements/
+review_needed: false
+---

leetcode/note/medium/36_valid_sudoku.md

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+---
+id: 36
+title: Valid Sudoku
+difficulty: Medium
+tags:
+  - array
+  - hash-table
+  - matrix
+status: unsolve
+date_solved: 2026-05-26
+leetcode_url: https://leetcode.com/problems/valid-sudoku/
+review_needed: false
+---

leetcode/note/medium/380_insert_delete_getrandom_o1.md

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+---
+id: 380
+title: Insert Delete GetRandom O(1)
+difficulty: Medium
+tags:
+  - array
+  - hash-table
+  - math
+  - randomized
+  - design
+status: unsolve
+date_solved: 2026-05-26
+leetcode_url: https://leetcode.com/problems/insert-delete-getrandom-o1/
+review_needed: false
+---

leetcode/note/medium/442_find_all_duplicates_in_an_array.md

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+---
+id: 442
+title: Find All Duplicates in an Array
+difficulty: Medium
+tags:
+  - array
+  - hash-table
+status: unsolve
+date_solved: 2026-05-26
+leetcode_url: https://leetcode.com/problems/find-all-duplicates-in-an-array/
+review_needed: false
+---

leetcode/note/medium/49_group_anagrams.md

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+---
+id: 49
+title: Group Anagrams
+difficulty: Medium
+tags:
+  - array
+  - hash-table
+  - string
+  - sorting
+status: unsolve
+date_solved: 2026-05-26
+leetcode_url: https://leetcode.com/problems/group-anagrams/
+review_needed: false
+---

leetcode/note/medium/560_subarray_sum_equals_k.md

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+---
+id: 560
+title: Subarray Sum Equals K
+difficulty: Medium
+tags:
+  - array
+  - hash-table
+  - prefix-sum
+status: unsolve
+date_solved: 2026-05-26
+leetcode_url: https://leetcode.com/problems/subarray-sum-equals-k/
+review_needed: false
+---