双指针

16. 3Sum Closest题目Given an array nums of n integers and an integer target, find three integers in nums such that the sum is closest to target. Return the sum of the three integers. You may assume that each input would have exactly one solution. Example: 123Given array nums = [-1, 2, 1, -4], and target = 1.The sum that is closest to the target is 2. (-1 + 2 + 1 = 2). 题目大意给定一个数组，要求在这个数组中找出 3 个数之和离 target 最近。 解题思路 初始值优化： 原代码中it初始化为...

977. Squares of a Sorted ArrayGiven an array of integers A sorted in non-decreasing order, return an array of the squares of each number, also in sorted non-decreasing order. Example 1: 12Input: [-4,-1,0,3,10]Output: [0,1,9,16,100] Example 2: 12Input: [-7,-3,2,3,11]Output: [4,9,9,49,121] Note: 1 <= A.length <= 10000 -10000 <= A[i] <= 10000 A is sorted in non-decreasing...

844. Backspace String Compare题目Given two strings S and T, return if they are equal when both are typed into empty text editors. # means a backspace character. Example 1: 123Input: S = "ab#c", T = "ad#c"Output: trueExplanation: Both S and T become "ac". Example 2: 123Input: S = "ab##", T = "c#d#"Output: trueExplanation: Both S and T become "". Example 3: 123Input: S = "a##c", T = "#a#c"Output: trueExplanation:...

922. Sort Array By Parity IIGiven an array of integers nums, half of the integers in nums are odd, and the other half are even. Sort the array so that whenever nums[i] is odd, i is odd, and whenever nums[i] is even, i is even. Return any answer array that satisfies this condition. Example 1: 123Input: nums = [4,2,5,7]Output: [4,5,2,7]Explanation: [4,7,2,5], [2,5,4,7], [2,7,4,5] would also have been accepted. Example 2: 12Input: nums = [2,3]Output: [2,3] 双指针解法： 初始化： 偶数索引指针 i 从 0 开始，每次移动 2...

905. Sort Array By ParityGiven an integer array nums, move all the even integers at the beginning of the array followed by all the odd integers. Return any array that satisfies this condition. Example 1: 123Input: nums = [3,1,2,4]Output: [2,4,3,1]Explanation: The outputs [4,2,3,1], [2,4,1,3], and [4,2,1,3] would also be accepted. Example 2: 12Input: nums = [0]Output: [0] 解法1：双指针12345678910111213141516class Solution{public: vector<int> sortArrayByParity(vector<int>...

1089. Duplicate Zeros题目Given a fixed length array arr of integers, duplicate each occurrence of zero, shifting the remaining elements to the right. Note that elements beyond the length of the original array are not written. Do the above modifications to the input array in place, do not return anything from your function. Example 1: 123Input: [1,0,2,3,0,4,5,0]Output: nullExplanation: After calling your function, the input array is modified to: [1,0,0,2,3,0,0,4] Example 2: 123Input:...

283. Move Zeroes题目Given an array nums, write a function to move all 0's to the end of it while maintaining the relative order of the non-zero elements. Example 1: 12Input: [0,1,0,3,12]Output: [1,3,12,0,0] Note: You must do this in-place without making a copy of the array. Minimize the total number of operations. 解法1：双指针1234567891011121314151617181920class Solution {public: void moveZeroes(vector<int>& nums) { int n = nums.size(); int i = 0; //...

26. Remove Duplicates from Sorted Array给你一个 非严格递增排列 的数组 nums ，请你** 原地** 删除重复出现的元素，使每个元素 只出现一次 ，返回删除后数组的新长度。元素的 相对顺序 应该保持 一致 。然后返回 nums 中唯一元素的个数。 考虑 nums 的唯一元素的数量为 k ，你需要做以下事情确保你的题解可以被通过： 更改数组 nums ，使 nums 的前 k 个元素包含唯一元素，并按照它们最初在 nums 中出现的顺序排列。nums 的其余元素与 nums 的大小不重要。 返回 k 。 判题标准: 系统会用下面的代码来测试你的题解: 123456789int[] nums = [...]; // 输入数组int[] expectedNums = [...]; // 长度正确的期望答案int k = removeDuplicates(nums); // 调用assert k == expectedNums.length;for (int i = 0; i < k; i++) { assert...