--- title: Two Pointers type: docs --- # Two Pointers ![](https://img.halfrost.com/Leetcode/Two_pointers.png) - 双指针滑动窗口的经典写法。右指针不断往右移，移动到不能往右移动为止(具体条件根据题目而定)。当右指针到最右边以后，开始挪动左指针，释放窗口左边界。第 3 题，第 76 题，第 209 题，第 424 题，第 438 题，第 567 题，第 713 题，第 763 题，第 845 题，第 881 题，第 904 题，第 978 题，第 992 题，第 1004 题，第 1040 题，第 1052 题。 ```c left, right := 0, -1 for left < len(s) { if right+1 < len(s) && freq[s[right+1]-'a'] == 0 { freq[s[right+1]-'a']++ right++ } else { freq[s[left]-'a']-- left++ } result = max(result, right-left+1) } ``` - 快慢指针可以查找重复数字，时间复杂度 O(n)，第 287 题。 - 替换字母以后，相同字母能出现连续最长的长度。第 424 题。 - SUM 问题集。第 1 题，第 15 题，第 16 题，第 18 题，第 167 题，第 923 题，第 1074 题。 | No. | Title | Solution | Difficulty | TimeComplexity | SpaceComplexity |Favorite| Acceptance | |:--------:|:------- | :--------: | :----------: | :----: | :-----: | :-----: |:-----: | |0003|Longest Substring Without Repeating Characters|[Go]({{< relref "/ChapterFour/0003.Longest-Substring-Without-Repeating-Characters.md" >}})|Medium| O(n)| O(1)|❤️|31.3%| |0011|Container With Most Water|[Go]({{< relref "/ChapterFour/0011.Container-With-Most-Water.md" >}})|Medium| O(n)| O(1)||52.2%| |0015|3Sum|[Go]({{< relref "/ChapterFour/0015.3Sum.md" >}})|Medium| O(n^2)| O(n)|❤️|27.8%| |0016|3Sum Closest|[Go]({{< relref "/ChapterFour/0016.3Sum-Closest.md" >}})|Medium| O(n^2)| O(1)|❤️|46.3%| |0018|4Sum|[Go]({{< relref "/ChapterFour/0018.4Sum.md" >}})|Medium| O(n^3)| O(n^2)|❤️|34.7%| |0019|Remove Nth Node From End of List|[Go]({{< relref "/ChapterFour/0019.Remove-Nth-Node-From-End-of-List.md" >}})|Medium| O(n)| O(1)||35.6%| |0026|Remove Duplicates from Sorted Array|[Go]({{< relref "/ChapterFour/0026.Remove-Duplicates-from-Sorted-Array.md" >}})|Easy| O(n)| O(1)||46.4%| |0027|Remove Element|[Go]({{< relref "/ChapterFour/0027.Remove-Element.md" >}})|Easy| O(n)| O(1)||49.1%| |0028|Implement strStr()|[Go]({{< relref "/ChapterFour/0028.Implement-strStr.md" >}})|Easy| O(n)| O(1)||35.1%| |0030|Substring with Concatenation of All Words|[Go]({{< relref "/ChapterFour/0030.Substring-with-Concatenation-of-All-Words.md" >}})|Hard| O(n)| O(n)|❤️|26.1%| |0042|Trapping Rain Water|[Go]({{< relref "/ChapterFour/0042.Trapping-Rain-Water.md" >}})|Hard| O(n)| O(1)|❤️|50.8%| |0061|Rotate List|[Go]({{< relref "/ChapterFour/0061.Rotate-List.md" >}})|Medium| O(n)| O(1)||31.6%| |0075|Sort Colors|[Go]({{< relref "/ChapterFour/0075.Sort-Colors.md" >}})|Medium| O(n)| O(1)|❤️|49.0%| |0076|Minimum Window Substring|[Go]({{< relref "/ChapterFour/0076.Minimum-Window-Substring.md" >}})|Hard| O(n)| O(n)|❤️|35.8%| |0080|Remove Duplicates from Sorted Array II|[Go]({{< relref "/ChapterFour/0080.Remove-Duplicates-from-Sorted-Array-II.md" >}})|Medium| O(n)| O(1||45.9%| |0086|Partition List|[Go]({{< relref "/ChapterFour/0086.Partition-List.md" >}})|Medium| O(n)| O(1)|❤️|43.1%| |0088|Merge Sorted Array|[Go]({{< relref "/ChapterFour/0088.Merge-Sorted-Array.md" >}})|Easy| O(n)| O(1)|❤️|40.6%| |0125|Valid Palindrome|[Go]({{< relref "/ChapterFour/0125.Valid-Palindrome.md" >}})|Easy| O(n)| O(1)||38.0%| |0141|Linked List Cycle|[Go]({{< relref "/ChapterFour/0141.Linked-List-Cycle.md" >}})|Easy| O(n)| O(1)|❤️|42.3%| |0142|Linked List Cycle II|[Go]({{< relref "/ChapterFour/0142.Linked-List-Cycle-II.md" >}})|Medium| O(n)| O(1)|❤️|39.4%| |0167|Two Sum II - Input array is sorted|[Go]({{< relref "/ChapterFour/0167.Two-Sum-II---Input-array-is-sorted.md" >}})|Easy| O(n)| O(1)||55.4%| |0209|Minimum Size Subarray Sum|[Go]({{< relref "/ChapterFour/0209.Minimum-Size-Subarray-Sum.md" >}})|Medium| O(n)| O(1)||39.2%| |0234|Palindrome Linked List|[Go]({{< relref "/ChapterFour/0234.Palindrome-Linked-List.md" >}})|Easy| O(n)| O(1)||40.3%| |0283|Move Zeroes|[Go]({{< relref "/ChapterFour/0283.Move-Zeroes.md" >}})|Easy| O(n)| O(1)||58.5%| |0287|Find the Duplicate Number|[Go]({{< relref "/ChapterFour/0287.Find-the-Duplicate-Number.md" >}})|Medium| O(n)| O(1)|❤️|57.2%| |0344|Reverse String|[Go]({{< relref "/ChapterFour/0344.Reverse-String.md" >}})|Easy| O(n)| O(1)||70.1%| |0345|Reverse Vowels of a String|[Go]({{< relref "/ChapterFour/0345.Reverse-Vowels-of-a-String.md" >}})|Easy| O(n)| O(1)||44.9%| |0349|Intersection of Two Arrays|[Go]({{< relref "/ChapterFour/0349.Intersection-of-Two-Arrays.md" >}})|Easy| O(n)| O(n) ||64.5%| |0350|Intersection of Two Arrays II|[Go]({{< relref "/ChapterFour/0350.Intersection-of-Two-Arrays-II.md" >}})|Easy| O(n)| O(n) ||51.9%| |0424|Longest Repeating Character Replacement|[Go]({{< relref "/ChapterFour/0424.Longest-Repeating-Character-Replacement.md" >}})|Medium| O(n)| O(1) ||48.0%| |0457|Circular Array Loop|[Go]({{< relref "/ChapterFour/0457.Circular-Array-Loop.md" >}})|Medium||||30.0%| |0524|Longest Word in Dictionary through Deleting|[Go]({{< relref "/ChapterFour/0524.Longest-Word-in-Dictionary-through-Deleting.md" >}})|Medium| O(n)| O(1) ||48.9%| |0532|K-diff Pairs in an Array|[Go]({{< relref "/ChapterFour/0532.K-diff-Pairs-in-an-Array.md" >}})|Medium| O(n)| O(n)||35.0%| |0567|Permutation in String|[Go]({{< relref "/ChapterFour/0567.Permutation-in-String.md" >}})|Medium| O(n)| O(1)|❤️|44.6%| |0632|Smallest Range Covering Elements from K Lists|[Go]({{< relref "/ChapterFour/0632.Smallest-Range-Covering-Elements-from-K-Lists.md" >}})|Hard||||54.0%| |0713|Subarray Product Less Than K|[Go]({{< relref "/ChapterFour/0713.Subarray-Product-Less-Than-K.md" >}})|Medium| O(n)| O(1)||40.4%| |0763|Partition Labels|[Go]({{< relref "/ChapterFour/0763.Partition-Labels.md" >}})|Medium| O(n)| O(1)|❤️|77.9%| |0826|Most Profit Assigning Work|[Go]({{< relref "/ChapterFour/0826.Most-Profit-Assigning-Work.md" >}})|Medium| O(n log n)| O(n)||39.0%| |0828|Count Unique Characters of All Substrings of a Given String|[Go]({{< relref "/ChapterFour/0828.Count-Unique-Characters-of-All-Substrings-of-a-Given-String.md" >}})|Hard| O(n)| O(1)|❤️|46.7%| |0838|Push Dominoes|[Go]({{< relref "/ChapterFour/0838.Push-Dominoes.md" >}})|Medium| O(n)| O(n)||49.7%| |0844|Backspace String Compare|[Go]({{< relref "/ChapterFour/0844.Backspace-String-Compare.md" >}})|Easy| O(n)| O(n) ||46.8%| |0845|Longest Mountain in Array|[Go]({{< relref "/ChapterFour/0845.Longest-Mountain-in-Array.md" >}})|Medium| O(n)| O(1) ||38.5%| |0881|Boats to Save People|[Go]({{< relref "/ChapterFour/0881.Boats-to-Save-People.md" >}})|Medium| O(n log n)| O(1) ||48.7%| |0904|Fruit Into Baskets|[Go]({{< relref "/ChapterFour/0904.Fruit-Into-Baskets.md" >}})|Medium| O(n log n)| O(1) ||42.9%| |0923|3Sum With Multiplicity|[Go]({{< relref "/ChapterFour/0923.3Sum-With-Multiplicity.md" >}})|Medium| O(n^2)| O(n) ||36.1%| |0925|Long Pressed Name|[Go]({{< relref "/ChapterFour/0925.Long-Pressed-Name.md" >}})|Easy| O(n)| O(1)||38.3%| |0930|Binary Subarrays With Sum|[Go]({{< relref "/ChapterFour/0930.Binary-Subarrays-With-Sum.md" >}})|Medium| O(n)| O(n) |❤️|44.3%| |0977|Squares of a Sorted Array|[Go]({{< relref "/ChapterFour/0977.Squares-of-a-Sorted-Array.md" >}})|Easy| O(n)| O(1)||72.2%| |0986|Interval List Intersections|[Go]({{< relref "/ChapterFour/0986.Interval-List-Intersections.md" >}})|Medium| O(n)| O(1)||68.1%| |0992|Subarrays with K Different Integers|[Go]({{< relref "/ChapterFour/0992.Subarrays-with-K-Different-Integers.md" >}})|Hard| O(n)| O(n)|❤️|50.5%| |1004|Max Consecutive Ones III|[Go]({{< relref "/ChapterFour/1004.Max-Consecutive-Ones-III.md" >}})|Medium| O(n)| O(1) ||60.6%| |1093|Statistics from a Large Sample|[Go]({{< relref "/ChapterFour/1093.Statistics-from-a-Large-Sample.md" >}})|Medium| O(n)| O(1) ||49.4%| |1234|Replace the Substring for Balanced String|[Go]({{< relref "/ChapterFour/1234.Replace-the-Substring-for-Balanced-String.md" >}})|Medium||||34.4%| |1658|Minimum Operations to Reduce X to Zero|[Go]({{< relref "/ChapterFour/1658.Minimum-Operations-to-Reduce-X-to-Zero.md" >}})|Medium||||33.4%| |1695|Maximum Erasure Value|[Go]({{< relref "/ChapterFour/1695.Maximum-Erasure-Value.md" >}})|Medium||||49.7%| |------------|-------------------------------------------------------|-------| ----------------| ---------------|-------------|-------------|-------------| ----------------------------------------------

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