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Commit 24105c7

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[新增] 新增题目 977. 有序数组的平方
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‎src/977_squaresOfASortedArray.ts

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/*
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977. 有序数组的平方
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难度:简单
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题目链接:https://leetcode.cn/problems/squares-of-a-sorted-array/
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给你一个按 非递减顺序 排序的整数数组 nums,返回 每个数字的平方 组成的新数组,要求也按 非递减顺序 排序。
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示例 1:
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输入:nums = [-4,-1,0,3,10]
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输出:[0,1,9,16,100]
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解释:平方后,数组变为 [16,1,0,9,100]
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排序后,数组变为 [0,1,9,16,100]
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示例 2:
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输入:nums = [-7,-3,2,3,11]
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输出:[4,9,9,49,121]
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提示:
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1 <= nums.length <= 104
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-104 <= nums[i] <= 104
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nums 已按 非递减顺序 排序
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进阶:
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请你设计时间复杂度为 O(n) 的算法解决本问题
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*/
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import { fileURLToPath } from 'url'
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import testCases from '../tests/testCases/977_squaresOfASortedArray.js'
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/**
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* 计算有序数组的平方
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* - LeetCode 入口
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* @param {number[]} nums - 待计算的非递减顺序排序的整数数组
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* @returns {number[]} 非递减顺序排序的整数结果数组
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*/
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export function sortedSquares (nums: number[]): number[] {
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// 初始化返回值
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const result: number[] = new Array<number>(nums.length)
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// 使用双指针法,从原数组前后向中间遍历
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let leftIndex: number = 0
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let rightIndex: number = nums.length - 1
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let targetIndex: number = nums.length - 1
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while (leftIndex <= rightIndex) {
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// 计算两个指针所处位置的平方
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const leftResult = nums[leftIndex] * nums[leftIndex]
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const rightResult = nums[rightIndex] * nums[rightIndex]
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// 判断左右两边平方结果的大小,将较大的结果依次从右向左放置在结果数组中
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if (leftResult > rightResult) {
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result[targetIndex--] = leftResult
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leftIndex++
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} else {
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result[targetIndex--] = rightResult
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rightIndex--
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}
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}
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return result
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}
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// Debug
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if (process.argv[1] === fileURLToPath(import.meta.url)) {
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const { input, expected } = testCases[0]
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const output = sortedSquares(input)
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console.log({ input, output, expected })
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}

‎tests/977_squaresOfASortedArray.test.ts

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import { describe, test, expect } from '@jest/globals'
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import testCases from './testCases/977_squaresOfASortedArray.js'
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import { sortedSquares } from '../src/977_squaresOfASortedArray.js'
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describe('977. Squares of a Sorted Array', () => {
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testCases.forEach(({ input, expected }, index) => {
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test(`Test case index: ${index}, Input: ${input.toString()}`, () => {
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expect(sortedSquares(input)).toEqual(expected)
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})
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})
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})
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export default [
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{ input: [-4, -1, 0, 3, 10], expected: [0, 1, 9, 16, 100] },
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{ input: [-7, -3, 2, 3, 11], expected: [4, 9, 9, 49, 121] }
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]

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