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スライディングウィンドウと Two Pointers

スライディングウィンドウは、配列や文字列の一区間を保ったまま両端を前に進めていく手法です。部分配列を毎回数え直す必要がなくなります。Two Pointers は同じ発想を一列または二列の数列に使うもので、全探索になりがちな問題を一回の走査で解けるようにします。

6 つの章は固定長ウィンドウから始まり、伸び縮みする可変長ウィンドウ、一列の Two Pointers、二列の Two Pointers、Three Pointers と進み、グループ分けループで終わります。ルートの最初の問題集なので、LeetCode を始めたばかりの人や、しばらく離れていて勘を取り戻したい人に向いています。

194 問レーティング 1165–28066 章
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一、Fixed-Length Sliding Window

§1.1 基礎

問題レーティング
1456. Maximum Number of Vowels in a Substring of Given Length1263
643. Maximum Average Subarray I1263
1343. Number of Sub Arrays of Size K AND Average Greater Than OR Equal to Threshold1317
2090. K Radius Subarray Averages1358
2379. Minimum Recolors to Get K Consecutive Black Blocks1360
2841. Maximum Sum of Almost Unique Subarray1546
2461. Maximum Sum of Distinct Subarrays with Length K1553
1423. Maximum Points You Can Obtain From Cards1574

§1.2 発展（任意）任意

問題レーティング
3679. Minimum Discards to Balance Inventory1639
1052. Grumpy Bookstore Owner1639
3439. Reschedule Meetings for Maximum Free Time I1729
3694. Distinct Points Reachable After Substring Removal1739
3652. Best Time to Buy AND Sell Stock Using Strategy1739
2134. Minimum Swaps to Group All 1s Together II1748
1652. Defuse the Bomb1748
1297. Maximum Number of Occurrences of a Substring1748
2653. Sliding Subarray Beauty1786
1888. Minimum Number of Flips to Make the Binary String Alternating2006
567. Permutation in String2006
438. Find All Anagrams in a String2006
30. Substring with Concatenation of All Words2006
2156. Find Substring with Given Hash Value2063
2953. Count Complete Substrings2449
1016. Binary String with Substrings Representing 1 to N2063

§1.3 その他（任意）任意

問題レーティング
2200. Find All K Distant Indices in an Array1266
2269. Find the K Beauty of a Number1280
1984. Minimum Difference Between Highest AND Lowest of K Scores1306
1461. Check If a String Contains All Binary Codes of Size K1504
220. Contains Duplicate III1504

二、Dynamic-Length Sliding Window (Two Pointers)

§2.1 短いほど条件を満たす / 最長・最大を求める

問題レーティング
3. Longest Substring Without Repeating Characters1263
3090. Maximum Length Substring with Two Occurrences1329
1493. Longest Subarray of 1s After Deleting One Element1423
3634. Minimum Removals to Balance Array1453
1208. Get Equal Substrings Within Budget1497
904. Fruit Into Baskets1516
1695. Maximum Erasure Value1529
2958. Length of Longest Subarray with at Most K Frequency1535
2024. Maximize the Confusion of an Exam1643
1004. Max Consecutive Ones III1656
1658. Minimum Operations to Reduce X to Zero1817
2730. Find the Longest Semi Repetitive Substring1638
2779. Maximum Beauty of an Array After Applying Operation1638
1838. Frequency of the Most Frequent Element1876
2516. Take K of Each Character From Left AND Right1948
2831. Find the Longest Equal Subarray1976
2271. Maximum White Tiles Covered by a Carpet2022
2106. Maximum Fruits Harvested After at Most K Steps2062
2555. Maximize Win From Two Segments2081
2009. Minimum Number of Operations to Make Array Continuous2084
1610. Maximum Number of Visible Points2147
2781. Length of the Longest Valid Substring2204
3411. Maximum Subarray with Equal Products2300
3413. Maximum Coins From K Consecutive Bags2374
395. Longest Substring with at Least K Repeating Characters2444
1763. Longest Nice Substring2444
2968. Apply Operations to Maximize Frequency Score2444
1040. Moving Stones Until Consecutive II2456

§2.2 長いほど条件を満たす / 最短・最小を求める

問題レーティング
209. Minimum Size Subarray Sum1263
2904. Shortest AND Lexicographically Smallest Beautiful String1914
1234. Replace the Substring for Balanced String1878
2875. Minimum Size Subarray in Infinite Array1914
76. Minimum Window Substring1592
632. Smallest Range Covering Elements From K Lists1592

§2.3 subarrayの個数を数える

問題レーティング
713. Subarray Product Less Than K1263
3258. Count Substrings That Satisfy K Constraint I1808
2302. Count Subarrays with Score Less Than K1808
2762. Continuous Subarrays1940
1358. Number of Substrings Containing All Three Characters1646
2962. Count Subarrays Where Max Element Appears at Least K Times1701
3306. Count Substrings with K Frequency Characters I1701
2799. Count Complete Subarrays in an Array1892
2537. Count the Number of Good Subarrays1892
3298. Count Substrings That Can Be Rearranged to Contain a String II1909
930. Binary Subarrays with Sum1592
1248. Count Number of Nice Subarrays1624
3306. Count of Substrings Containing Every Vowel AND K Consonants II2200
992. Subarrays with K Different Integers2210

§2.4 その他（任意）任意

問題レーティング
825. Friends of Appropriate Ages1697
2401. Longest Nice Subarray1750
1156. Swap for Longest Repeated Character Substring1787
424. Longest Repeating Character Replacement1787
438. Find All Anagrams in a String1787
1712. Ways to Split Array Into Three Subarrays2079

三、単一列の Two Pointers

§3.1 両端から向かい合うTwo Pointers

問題レーティング
344. Reverse String1263
3643. Flip Square Submatrix Vertically1235
541. Reverse String II1263
557. Reverse Words in a String III1263
345. Reverse Vowels of a String1263
917. Reverse Only Letters1263
125. Valid Palindrome1263
1750. Minimum Length of String After Deleting Similar Ends1502
2105. Watering Plants II1507
977. Squares of a Sorted Array1263
658. Find K Closest Elements1263
1471. The K Strongest Values in an Array1263
167. Two Sum II Input Array Is Sorted1263
633. Sum of Square Numbers1263
2824. Count Pairs Whose Sum Is Less Than Target1263
2563. Count the Number of Fair Pairs1263
15. 3sum1263
16. 3sum Closest1263
18. 4sum1263
611. Valid Triangle Number1263
1577. Number of Ways Where Square of Number Is Equal to Product of Two Numbers1263
923. 3sum with Multiplicity1711
948. Bag of Tokens1762
11. Container with Most Water1263
42. Trapping Rain Water1263
1616. Split Two Strings to Make Palindrome1868
1498. Number of Subsequences That Satisfy the Given Sum Condition2276
1782. Count Pairs of Nodes2457

§3.2 同じ向きに進むTwo Pointers

問題レーティング
611. Valid Triangle Number1263
3649. Number of Perfect Pairs1716
1574. Shortest Subarray to Be Removed to Make Array Sorted1932
2972. Count the Number of Incremovable Subarrays II2153
2122. Recover the Original Array2159
2234. Maximum Total Beauty of the Gardens2562

§3.3 中心から外へ広がるTwo Pointers

問題レーティング
1793. Maximum Score of a Good Subarray1946
976. Largest Perimeter Triangle1263

§3.4 インプレース変更

問題レーティング
27. Remove Element1263
26. Remove Duplicates From Sorted Array1263
80. Remove Duplicates From Sorted Array II1263
2273. Find Resultant Array After Removing Anagrams1295
3684. Maximize Sum of at Most K Distinct Elements1263
283. Move Zeroes1263
905. Sort Array by Parity1263
922. Sort Array by Parity II1263
3467. Transform Array by Parity1263
2460. Apply Operations to an Array1263
1089. Duplicate Zeros1263
75. Sort Colors1263

四、二列の Two Pointers

§4.1 Two Pointers

問題レーティング
2109. Adding Spaces to a String1315
2540. Minimum Common Value1315
88. Merge Sorted Array1315
2570. Merge Two 2D Arrays by Summing Values1315
350. Intersection of Two Arrays II1315
1855. Maximum Distance Between a Pair of Values1515
1385. Find the Distance Value Between Two Arrays1315
925. Long Pressed Name1315
809. Expressive Words1605
2337. Move Pieces to Obtain a String1693
777. Swap Adjacent in Lr String1693
844. Backspace String Compare1315
986. Interval List Intersections1315
1537. Get the Maximum Score1961

§4.2 subsequence判定

問題レーティング
392. Is Subsequence1315
524. Longest Word in Dictionary Through Deleting1315
2486. Append Characters to String to Make Subsequence1363
2825. Make String a Subsequence Using Cyclic Increments1415
1023. Camelcase Matching1537
3132. Find the Integer Added to Array II1620
522. Longest Uncommon Subsequence II1700
1898. Maximum Number of Removable Characters1913
2565. Subsequence with the Minimum Score2432
3302. Find the Lexicographically Smallest Valid Sequence2474

五、Three Pointers

基礎問題

問題レーティング
2367. Number of Arithmetic Triplets1263
2563. Count the Number of Fair Pairs1721
795. Number of Subarrays with Bounded Maximum1817
2444. Count Subarrays with Fixed Bounds2093
3347. Maximum Frequency of an Element After Performing Operations II2156

発展的な思考

問題レーティング
3464. Maximize the Distance Between Points on a Square2806

六、Grouped Loop

基礎問題

問題レーティング
485. Max Consecutive Ones1263
1446. Consecutive Characters1165
1869. Longer Contiguous Segments of Ones Than Zeros1205
2414. Length of the Longest Alphabetical Continuous Substring1222
3456. Find Special Substring of Length K1244
2273. Find Resultant Array After Removing Anagrams1295
2348. Number of Zero Filled Subarrays1316
1513. Number of Substrings with Only 1s1351
1957. Delete Characters to Make Fancy String1358
674. Longest Continuous Increasing Subsequence1263
3708. Longest Fibonacci Subarray1381
696. Count Binary Substrings1263
978. Longest Turbulent Subarray1393
2110. Number of Smooth Descent Periods of a Stock1408
228. Summary Ranges1263
2760. Longest Even Odd Subarray with Threshold1420
1887. Reduction Operations to Make the Array Elements Equal1428
845. Longest Mountain in Array1437
2038. Remove Colored Pieces If Both Neighbors Are the Same Color1468
2900. Longest Unequal Adjacent Groups Subsequence I1469
1759. Count Number of Homogenous Substrings1491
3011. Find If Array Can Be Sorted1497
1578. Minimum Time to Make Rope Colorful1574
1839. Longest Substring of All Vowels in Order1580
2765. Longest Alternating Subarray1581
3255. Find the Power of K Size Subarrays II1595
3350. Adjacent Increasing Subarrays Detection II1600
3105. Longest Strictly Increasing OR Strictly Decreasing Subarray1600
838. Push Dominoes1638
467. Unique Substrings in Wraparound String1700
3499. Maximize Active Section with Trade I1729
413. Arithmetic Slices1263
68. Text Justification1263
135. Candy1263
2948. Make Lexicographically Smallest Array by Swapping Elements2047
2593. Find Score of an Array After Marking All Elements1263
3640. Trionic Array II2278

新しいルートは必ずこの問題集の最初のセクションから始まり、3 つの任意セクションは印が付いたうえで発展編に回されるので、先へ進む妨げになりません。

レーティングは zerotrac さんによる LeetCode コンテストレーティングです。zerotrac のレーティングがない問題は「未評価」と表示されます。

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