LeetCode 300. Longest Increasing Subsequence (javascript)

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:

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:

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

Example 3:

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

Constraints:

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

Idea:

dp[i] represents the length of the longest increasing subsequence of nums[0...i]
dp[0] = 1
dp[i] = max(dp[j]'s) + 1 if j < i when nums[i] > nums[j]
result: find the max of all dp[i]'s

Solution:

/**
 * @param {number[]} nums
 * @return {number}
 */
var lengthOfLIS = function(nums) {
    let dp = new Array(nums.length);
    dp[0] = 1;
    for (let i = 0; i < nums.length; i++) {
        // local max
        let max = 0;
        for (let j = 0; j < i; j++) {
            if (nums[i] > nums[j]) {
                max = Math.max(dp[j], max);
            }
        }
        dp[i] = max + 1;
    }
    // result: find the max of all dp[i]'s
    return Math.max(...dp);
};