0300-longest-increasing-subsequence.js

/**
 * DP - Bottom Up
 * Array - Tabulation
 * Time O(N^2) | Space O(N)
 * https://leetcode.com/problems/longest-increasing-subsequence/
 * @param {number[]} nums
 * @return {number}
 */
var lengthOfLIS = (nums) => {
    const tabu = initTabu(nums); /*               | Space O(N) */

    linearSearch(nums, tabu); /* Time O(N * N) | Space O(N)*/

    return Math.max(...tabu); /* Time O(N) */
};

const initTabu = (nums) => new Array(nums.length).fill(1);

var linearSearch = (nums, tabu) => {
    for (let right = 1; right < nums.length; right++) {
        /* Time O(N) */
        for (let left = 0; left < right; left++) {
            /* Time O(N) */
            const canUpdate = nums[left] < nums[right];
            if (!canUpdate) continue;

            const [_left, _right] = [tabu[left] + 1, tabu[right]];
            tabu[right] = Math.max(_right, _left); /* Space O(N) */
        }
    }
};

/**
 * Array - Subsequence
 * Time O(N^2) | Space O(N)
 * https://leetcode.com/problems/longest-increasing-subsequence/
 * @param {number[]} nums
 * @return {number}
 */
var lengthOfLIS = (nums) => {
    const subsequence = linearSort(nums); /* Time O(N * N) | Space O(N) */

    return subsequence.length;
};

var linearSort = (nums, subsequence = []) => {
    for (const num of nums) {
        /* Time O(N) */
        const max = subsequence[subsequence.length - 1];

        const canAdd = max < num;
        if (canAdd) {
            subsequence.push(num);
            continue;
        } /* Space O(N) */

        const index = getMax(subsequence, num); /* Time O(N) */

        subsequence[index] = num;
    }

    return subsequence;
};

const getMax = (subsequence, num, index = 0) => {
    const isLess = () => subsequence[index] < num;
    while (isLess()) index++; /* Time O(N) */

    return index;
};

/**
 * Array - Subsequence
 * Time O(N * log(N)) | Space O(N)
 * https://leetcode.com/problems/longest-increasing-subsequence/
 * @param {number[]} nums
 * @return {number}
 */
var lengthOfLIS = (nums) => {
    const subsequence = logarithmicSort(nums); /* Time O(N * log(N) */

    return subsequence.length;
};

var logarithmicSort = (nums, subsequence = []) => {
    for (const num of nums) {
        /* Time O(N) */
        const max = subsequence[subsequence.length - 1];

        const canAdd = max < num;
        if (canAdd) {
            subsequence.push(num);
            continue;
        } /* Space O(N) */

        const index = binarySearch(num, subsequence); /* Time O(log(N)) */

        subsequence[index] = num;
    }

    return subsequence;
};

const binarySearch = (num, subsequence) => {
    let [left, right] = [0, subsequence.length - 1];

    while (left < right) {
        /* Time O(log(N)) */
        const mid = (left + right) >> 1;
        const guess = subsequence[mid];

        const isNumTarget = num === guess;
        if (isNumTarget) return mid;

        const isNumGreater = guess < num;
        if (isNumGreater) left = mid + 1;

        const isNumLess = num < guess;
        if (isNumLess) right = mid;
    }

    return left;
};