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Commit eff8227

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[新增] 新增题目 209. 长度最小的子数组
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‎src/209_minimumSizeSubarraySum.ts

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/*
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209. 长度最小的子数组
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难度:中等
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题目链接:https://leetcode.cn/problems/minimum-size-subarray-sum/
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给定一个含有 n 个正整数的数组和一个正整数 target 。
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找出该数组中满足其和 ≥ target 的长度最小的 连续子数组 [numsl, numsl+1, ..., numsr-1, numsr] ,并返回其长度。如果不存在符合条件的子数组,返回 0 。
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示例 1:
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输入:target = 7, nums = [2,3,1,2,4,3]
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输出:2
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解释:子数组 [4,3] 是该条件下的长度最小的子数组。
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示例 2:
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输入:target = 4, nums = [1,4,4]
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输出:1
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示例 3:
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输入:target = 11, nums = [1,1,1,1,1,1,1,1]
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输出:0
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提示:
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1 <= target <= 109
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1 <= nums.length <= 105
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1 <= nums[i] <= 105
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进阶:
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如果你已经实现 O(n) 时间复杂度的解法, 请尝试设计一个 O(n log(n)) 时间复杂度的解法。
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*/
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import { fileURLToPath } from 'url'
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import testCases from '../tests/testCases/209_minimumSizeSubarraySum.js'
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/**
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* 长度最小的子数组
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* - LeetCode 入口
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* @param {number} target - 要大于或等于的正整数
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* @param {number[]} nums - 整数数组
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* @returns {number} 相加大于等于目标整数的最小子数组的长度
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*/
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export function minSubArrayLen (target: number, nums: number[]): number {
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// 使用无限初始化返回值,在之后的操作中要判断子数组长度是否比返回值要小
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let result: number = Infinity
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// 初始化子数组每个元素相加的值
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let sum: number = 0
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// 使用滑动窗口算法,初始化滑动窗口的起止下标为 0
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// 每一次循环将窗口的右指针(结束指针)加一(向右移动一位),直到移动到整个数组的末位
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for (let leftIndex = 0, rightIndex = 0; rightIndex < nums.length; rightIndex++) {
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// 每一次循环中将右指针所在的值累计相加
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sum += nums[rightIndex]
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// 遇到子数组相加的值达到目标值
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// 计算子数组长度,用更小的长度替换 result
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// sum 减去当前子数组左指针(起始指针)所在的值
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// 将左指针加一(向右移动一位),缩小窗口范围,继续判断更小的窗口中的值相加是否能满足目标
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while (sum >= target) {
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const subArrayLength = rightIndex - leftIndex + 1
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if (subArrayLength < result) result = subArrayLength
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sum -= nums[leftIndex]
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leftIndex++
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}
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}
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// 如果经历操作后返回值依然为初始的无限,则说明整个 nums 的值相加也无法满足目标,按要求返回 0
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// 否则返回操作中找到的最小子数组长度
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return result === Infinity ? 0 : 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 = minSubArrayLen(input.target, input.nums)
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console.log({ input, output, expected })
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}
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import { describe, test, expect } from '@jest/globals'
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import testCases from './testCases/209_minimumSizeSubarraySum.js'
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import { minSubArrayLen } from '../src/209_minimumSizeSubarraySum.js'
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describe('209. Minimum Size Subarray Sum', () => {
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testCases.forEach(({ input, expected }, index) => {
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test(`Test case index: ${index}`, () => {
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expect(minSubArrayLen(input.target, input.nums)).toEqual(expected)
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})
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})
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})
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export default [
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{
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input: {
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target: 7,
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nums: [2, 3, 1, 2, 4, 3]
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},
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expected: 2
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},
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{
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input: {
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target: 4,
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nums: [1, 4, 4]
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},
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expected: 1
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},
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{
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input: {
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target: 11,
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nums: [1, 1, 1, 1, 1, 1, 1, 1]
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},
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expected: 0
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}
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]

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