--- title: 2.03 ✅ Two Pointers type: docs weight: 3 --- # 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/0001~0099/0003.Longest-Substring-Without-Repeating-Characters.md" >}})|Medium| O(n)| O(1)|❤️|31.6%| |0011|Container With Most Water|[Go]({{< relref "/ChapterFour/0001~0099/0011.Container-With-Most-Water.md" >}})|Medium| O(n)| O(1)||52.9%| |0015|3Sum|[Go]({{< relref "/ChapterFour/0001~0099/0015.3Sum.md" >}})|Medium| O(n^2)| O(n)|❤️|28.3%| |0016|3Sum Closest|[Go]({{< relref "/ChapterFour/0001~0099/0016.3Sum-Closest.md" >}})|Medium| O(n^2)| O(1)|❤️|46.3%| |0018|4Sum|[Go]({{< relref "/ChapterFour/0001~0099/0018.4Sum.md" >}})|Medium| O(n^3)| O(n^2)|❤️|35.1%| |0019|Remove Nth Node From End of List|[Go]({{< relref "/ChapterFour/0001~0099/0019.Remove-Nth-Node-From-End-of-List.md" >}})|Medium| O(n)| O(1)||36.1%| |0026|Remove Duplicates from Sorted Array|[Go]({{< relref "/ChapterFour/0001~0099/0026.Remove-Duplicates-from-Sorted-Array.md" >}})|Easy| O(n)| O(1)||46.8%| |0027|Remove Element|[Go]({{< relref "/ChapterFour/0001~0099/0027.Remove-Element.md" >}})|Easy| O(n)| O(1)||49.5%| |0028|Implement strStr()|[Go]({{< relref "/ChapterFour/0001~0099/0028.Implement-strStr.md" >}})|Easy| O(n)| O(1)||35.4%| |0030|Substring with Concatenation of All Words|[Go]({{< relref "/ChapterFour/0001~0099/0030.Substring-with-Concatenation-of-All-Words.md" >}})|Hard| O(n)| O(n)|❤️|26.4%| |0042|Trapping Rain Water|[Go]({{< relref "/ChapterFour/0001~0099/0042.Trapping-Rain-Water.md" >}})|Hard| O(n)| O(1)|❤️|51.7%| |0061|Rotate List|[Go]({{< relref "/ChapterFour/0001~0099/0061.Rotate-List.md" >}})|Medium| O(n)| O(1)||32.0%| |0075|Sort Colors|[Go]({{< relref "/ChapterFour/0001~0099/0075.Sort-Colors.md" >}})|Medium| O(n)| O(1)|❤️|49.9%| |0076|Minimum Window Substring|[Go]({{< relref "/ChapterFour/0001~0099/0076.Minimum-Window-Substring.md" >}})|Hard| O(n)| O(n)|❤️|36.3%| |0080|Remove Duplicates from Sorted Array II|[Go]({{< relref "/ChapterFour/0001~0099/0080.Remove-Duplicates-from-Sorted-Array-II.md" >}})|Medium| O(n)| O(1||46.4%| |0086|Partition List|[Go]({{< relref "/ChapterFour/0001~0099/0086.Partition-List.md" >}})|Medium| O(n)| O(1)|❤️|44.8%| |0088|Merge Sorted Array|[Go]({{< relref "/ChapterFour/0001~0099/0088.Merge-Sorted-Array.md" >}})|Easy| O(n)| O(1)|❤️|40.9%| |0125|Valid Palindrome|[Go]({{< relref "/ChapterFour/0100~0199/0125.Valid-Palindrome.md" >}})|Easy| O(n)| O(1)||38.6%| |0141|Linked List Cycle|[Go]({{< relref "/ChapterFour/0100~0199/0141.Linked-List-Cycle.md" >}})|Easy| O(n)| O(1)|❤️|43.1%| |0142|Linked List Cycle II|[Go]({{< relref "/ChapterFour/0100~0199/0142.Linked-List-Cycle-II.md" >}})|Medium| O(n)| O(1)|❤️|40.1%| |0167|Two Sum II - Input array is sorted|[Go]({{< relref "/ChapterFour/0100~0199/0167.Two-Sum-II-Input-array-is-sorted.md" >}})|Easy| O(n)| O(1)||55.9%| |0209|Minimum Size Subarray Sum|[Go]({{< relref "/ChapterFour/0200~0299/0209.Minimum-Size-Subarray-Sum.md" >}})|Medium| O(n)| O(1)||39.9%| |0234|Palindrome Linked List|[Go]({{< relref "/ChapterFour/0200~0299/0234.Palindrome-Linked-List.md" >}})|Easy| O(n)| O(1)||42.1%| |0283|Move Zeroes|[Go]({{< relref "/ChapterFour/0200~0299/0283.Move-Zeroes.md" >}})|Easy| O(n)| O(1)||58.7%| |0287|Find the Duplicate Number|[Go]({{< relref "/ChapterFour/0200~0299/0287.Find-the-Duplicate-Number.md" >}})|Medium| O(n)| O(1)|❤️|58.0%| |0344|Reverse String|[Go]({{< relref "/ChapterFour/0300~0399/0344.Reverse-String.md" >}})|Easy| O(n)| O(1)||70.7%| |0345|Reverse Vowels of a String|[Go]({{< relref "/ChapterFour/0300~0399/0345.Reverse-Vowels-of-a-String.md" >}})|Easy| O(n)| O(1)||45.3%| |0349|Intersection of Two Arrays|[Go]({{< relref "/ChapterFour/0300~0399/0349.Intersection-of-Two-Arrays.md" >}})|Easy| O(n)| O(n) ||65.4%| |0350|Intersection of Two Arrays II|[Go]({{< relref "/ChapterFour/0300~0399/0350.Intersection-of-Two-Arrays-II.md" >}})|Easy| O(n)| O(n) ||52.2%| |0424|Longest Repeating Character Replacement|[Go]({{< relref "/ChapterFour/0400~0499/0424.Longest-Repeating-Character-Replacement.md" >}})|Medium| O(n)| O(1) ||48.4%| |0457|Circular Array Loop|[Go]({{< relref "/ChapterFour/0400~0499/0457.Circular-Array-Loop.md" >}})|Medium||||30.4%| |0524|Longest Word in Dictionary through Deleting|[Go]({{< relref "/ChapterFour/0500~0599/0524.Longest-Word-in-Dictionary-through-Deleting.md" >}})|Medium| O(n)| O(1) ||50.1%| |0532|K-diff Pairs in an Array|[Go]({{< relref "/ChapterFour/0500~0599/0532.K-diff-Pairs-in-an-Array.md" >}})|Medium| O(n)| O(n)||35.6%| |0567|Permutation in String|[Go]({{< relref "/ChapterFour/0500~0599/0567.Permutation-in-String.md" >}})|Medium| O(n)| O(1)|❤️|44.5%| |0632|Smallest Range Covering Elements from K Lists|[Go]({{< relref "/ChapterFour/0600~0699/0632.Smallest-Range-Covering-Elements-from-K-Lists.md" >}})|Hard||||54.6%| |0713|Subarray Product Less Than K|[Go]({{< relref "/ChapterFour/0700~0799/0713.Subarray-Product-Less-Than-K.md" >}})|Medium| O(n)| O(1)||40.6%| |0763|Partition Labels|[Go]({{< relref "/ChapterFour/0700~0799/0763.Partition-Labels.md" >}})|Medium| O(n)| O(1)|❤️|78.1%| |0826|Most Profit Assigning Work|[Go]({{< relref "/ChapterFour/0800~0899/0826.Most-Profit-Assigning-Work.md" >}})|Medium| O(n log n)| O(n)||39.3%| |0828|Count Unique Characters of All Substrings of a Given String|[Go]({{< relref "/ChapterFour/0800~0899/0828.Count-Unique-Characters-of-All-Substrings-of-a-Given-String.md" >}})|Hard| O(n)| O(1)|❤️|46.9%| |0838|Push Dominoes|[Go]({{< relref "/ChapterFour/0800~0899/0838.Push-Dominoes.md" >}})|Medium| O(n)| O(n)||50.1%| |0844|Backspace String Compare|[Go]({{< relref "/ChapterFour/0800~0899/0844.Backspace-String-Compare.md" >}})|Easy| O(n)| O(n) ||47.2%| |0845|Longest Mountain in Array|[Go]({{< relref "/ChapterFour/0800~0899/0845.Longest-Mountain-in-Array.md" >}})|Medium| O(n)| O(1) ||38.7%| |0881|Boats to Save People|[Go]({{< relref "/ChapterFour/0800~0899/0881.Boats-to-Save-People.md" >}})|Medium| O(n log n)| O(1) ||49.1%| |0904|Fruit Into Baskets|[Go]({{< relref "/ChapterFour/0900~0999/0904.Fruit-Into-Baskets.md" >}})|Medium| O(n log n)| O(1) ||43.0%| |0923|3Sum With Multiplicity|[Go]({{< relref "/ChapterFour/0900~0999/0923.3Sum-With-Multiplicity.md" >}})|Medium| O(n^2)| O(n) ||40.9%| |0925|Long Pressed Name|[Go]({{< relref "/ChapterFour/0900~0999/0925.Long-Pressed-Name.md" >}})|Easy| O(n)| O(1)||37.2%| |0930|Binary Subarrays With Sum|[Go]({{< relref "/ChapterFour/0900~0999/0930.Binary-Subarrays-With-Sum.md" >}})|Medium| O(n)| O(n) |❤️|44.9%| |0977|Squares of a Sorted Array|[Go]({{< relref "/ChapterFour/0900~0999/0977.Squares-of-a-Sorted-Array.md" >}})|Easy| O(n)| O(1)||71.8%| |0986|Interval List Intersections|[Go]({{< relref "/ChapterFour/0900~0999/0986.Interval-List-Intersections.md" >}})|Medium| O(n)| O(1)||68.6%| |0992|Subarrays with K Different Integers|[Go]({{< relref "/ChapterFour/0900~0999/0992.Subarrays-with-K-Different-Integers.md" >}})|Hard| O(n)| O(n)|❤️|50.9%| |1004|Max Consecutive Ones III|[Go]({{< relref "/ChapterFour/1000~1099/1004.Max-Consecutive-Ones-III.md" >}})|Medium| O(n)| O(1) ||60.9%| |1093|Statistics from a Large Sample|[Go]({{< relref "/ChapterFour/1000~1099/1093.Statistics-from-a-Large-Sample.md" >}})|Medium| O(n)| O(1) ||48.6%| |1234|Replace the Substring for Balanced String|[Go]({{< relref "/ChapterFour/1200~1299/1234.Replace-the-Substring-for-Balanced-String.md" >}})|Medium||||34.6%| |1658|Minimum Operations to Reduce X to Zero|[Go]({{< relref "/ChapterFour/1600~1699/1658.Minimum-Operations-to-Reduce-X-to-Zero.md" >}})|Medium||||33.3%| |1695|Maximum Erasure Value|[Go]({{< relref "/ChapterFour/1600~1699/1695.Maximum-Erasure-Value.md" >}})|Medium||||49.2%| |------------|-------------------------------------------------------|-------| ----------------| ---------------|-------------|-------------|-------------| ----------------------------------------------

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