LeetCode-300. Longest Increasing Subsequence

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问题描述

Given an integer array nums, return the length of the longest strictly increasing subsequence.

A subsequence is a sequence that can be derived from an array by deleting some or no elements without changing the order of the remaining elements. For example, [3,6,2,7] is a subsequence of the array [0,3,1,6,2,2,7].

Example 1:

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Input: nums = [10,9,2,5,3,7,101,18]
Output: 4
Explanation: The longest increasing subsequence is [2,3,7,101], therefore the length is 4.

Example 2:

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

Example 3:

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Input: nums = [7,7,7,7,7,7,7]
Output: 1

Constraints:

  • 1 <= nums.length <= 2500
  • -104 <= nums[i] <= 104

解答

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/*
 * @Description: 300. Longest Increasing Subsequence
 * @Author: libk
 * @Github: https://github.com/libk
 */
/**
 * @param {number[]} nums
 * @return {number}
 */
const lengthOfLIS = function (nums) {
  if (!nums || !nums.length) {
    return 0
  }

  const dp = new Array(nums.length).fill(1)
  let maxLen = 1

  for (let i = 1; i < nums.length; i++) {
    for (let j = 0; j < i; j++) {
      if (nums[i] > nums[j]) {
        dp[i] = Math.max(dp[i], dp[j] + 1)
      }
    }
    maxLen = Math.max(maxLen, dp[i])
  }
  return maxLen
}