shortest-unsorted-continuous-subarray.md

581. Shortest Unsorted Continuous Subarray - 最短无序连续子数组

Tags - 题目标签

Description - 题目描述

EN:

Given an integer array nums, you need to find one continuous subarray such that if you only sort this subarray in non-decreasing order, then the whole array will be sorted in non-decreasing order.

Return the shortest such subarray and output its length.

 

Example 1:

Input: nums = [2,6,4,8,10,9,15]
Output: 5
Explanation: You need to sort [6, 4, 8, 10, 9] in ascending order to make the whole array sorted in ascending order.

Example 2:

Input: nums = [1,2,3,4]
Output: 0

Example 3:

Input: nums = [1]
Output: 0

 

Constraints:

• 1 <= nums.length <= 104
• -105 <= nums[i] <= 105

 

Follow up: Can you solve it in O(n) time complexity?

ZH-CN:

给你一个整数数组 nums ，你需要找出一个 连续子数组 ，如果对这个子数组进行升序排序，那么整个数组都会变为升序排序。

请你找出符合题意的 最短 子数组，并输出它的长度。

 

示例 1：

输入：nums = [2,6,4,8,10,9,15]
输出：5
解释：你只需要对 [6, 4, 8, 10, 9] 进行升序排序，那么整个表都会变为升序排序。

示例 2：

输入：nums = [1,2,3,4]
输出：0

示例 3：

输入：nums = [1]
输出：0

 

提示：

• 1 <= nums.length <= 104
• -105 <= nums[i] <= 105

 

进阶：你可以设计一个时间复杂度为 O(n) 的解决方案吗？

Link - 题目链接

LeetCode - LeetCode-CN

Latest Accepted Submissions - 最近一次 AC 的提交

Language	Runtime	Memory	Submission Time
typescript	100 ms	46.4 MB	2023/08/12 19:38

function findUnsortedSubarray(nums: number[]): number {
  if (isSorted(nums)) {
    return 0;
  }

  const sortedArr = [...nums].sort((a, b) => a - b);

  let start = -1, end = -1;

  for (let i = 0; i < nums.length; i++) {
    if (nums[i] !== sortedArr[i]) {
      start = i;
      break;
    }
  }

  for (let j = nums.length - 1; j > 0; j--) {
    if (nums[j] !== sortedArr[j]) {
      end = j;
      break;
    }
  }

  return end - start + 1;
};

const isSorted = (nums: number[]) => {
  if (nums.length <= 1) {
    return true;
  }
  for (let i = 1; i < nums.length; i++) {
    if (nums[i] < nums[i - 1]) {
      return false;
    }
  }

  return true;
}

My Notes - 我的笔记

简单排序之后比较即可。

function findUnsortedSubarray(nums: number[]): number {
  if (isSorted(nums)) {
    return 0;
  }

  const sortedArr = [...nums].sort((a, b) => a - b);

  let start = -1, end = -1;

  for (let i = 0; i < nums.length; i++) {
    if (nums[i] !== sortedArr[i]) {
      start = i;
      break;
    }
  }

  for (let j = nums.length - 1; j > 0; j--) {
    if (nums[j] !== sortedArr[j]) {
      end = j;
      break;
    }
  }

  return end - start + 1;
};

const isSorted = (nums: number[]) => {
  if (nums.length <= 1) {
    return true;
  }
  for (let i = 1; i < nums.length; i++) {
    if (nums[i] < nums[i - 1]) {
      return false;
    }
  }

  return true;
}