0045-jump-game-ii.js

/**
 * https://leetcode.com/problems/jump-game-ii/
 * Time O(N) | Space O(1)
 * @param {number[]} nums
 * @return {number}
 */
var jump = function (nums) {
    let [left, right, jumps] = [0, 0, 0];

    while (right < nums.length - 1) {
        const maxReach = getMaxReach(nums, left, right);

        left = right + 1;
        right = maxReach;
        jumps += 1;
    }

    return jumps;
};

const getMaxReach = (nums, left, right, maxReach = 0) => {
    for (let i = left; i < right + 1; i++) {
        const reach = nums[i] + i;
        maxReach = Math.max(maxReach, reach);
    }

    return maxReach;
};

/**
 * https://leetcode.com/problems/jump-game-ii/
 * Time O(N) | Space O(1)
 * @param {number[]} nums
 * @return {number}
 */
var jump = function (nums) {
    let [jumps, currentJumpEnd, farthest] = [0, 0, 0];

    for (let i = 0; i < nums.length - 1; i++) {
        farthest = Math.max(farthest, i + nums[i]);

        const canJump = i === currentJumpEnd;
        if (canJump) {
            jumps++;
            currentJumpEnd = farthest;
        }
    }

    return jumps;
};