Jump Game II

You are given a 0-indexed array of integers nums of length n. You are initially positioned at nums[0].

Each element nums[i] represents the maximum length of a forward jump from index i. In other words, if you are at nums[i], you can jump to any nums[i + j] where:

• 0 <= j <= nums[i] and
• i + j < n

Return the minimum number of jumps to reach nums[n - 1]. The test cases are generated such that you can reach nums[n - 1].

Example 1:

Input: nums = [2,3,1,1,4]
Output: 2
Explanation: The minimum number of jumps to reach the last index is 2. Jump 1 step from index 0 to 1, then 3 steps to the last index.

Example 2:

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

Constraints:

• 1 <= nums.length <= 104
• 0 <= nums[i] <= 1000
• It's guaranteed that you can reach nums[n - 1].

Solution:

# @param {Integer[]} nums
# @return {Integer}
def jump(nums)
    n = nums.length
    return 0 if n == 1

    jumps = 0
    farthest = 0
    current_end = 0

    (0...n-1).each do |i|
        farthest = [farthest, i + nums[i]].max

        if i == current_end
            jumps += 1
            current_end = farthest

            return jumps if current_end >= n - 1
        end
    end

    return jumps
end