LeetCode/rb/rotate-array.rb

# @param {Integer[]} nums
# @param {Integer} k
# @return {Void} Do not return anything, modify nums in-place instead.
def rotate(nums, k)
    def reverse(nums, from, to)
        while from < to do
            nums[from], nums[to] = nums[to], nums[from]

            from += 1
            to -= 1
        end
    end

    k = k % nums.size
    reverse(nums, 0, nums.size - 1)
    reverse(nums, 0, k - 1)
    reverse(nums, k, nums.size - 1)
end

RSpec.describe "rotate" do
    it "nums = [1,2,3,4,5,6,7], k = 0" do
        nums = [1,2,3,4,5,6,7]
        k = 0

        rotate(nums, k)
        expect(nums).to eq([1,2,3,4,5,6,7])
    end

    it "nums = [1,2,3,4,5,6,7], k = 1" do
        nums = [1,2,3,4,5,6,7]
        k = 1

        rotate(nums, k)
        expect(nums).to eq([7,1,2,3,4,5,6])
    end

    it "nums = [1,2,3,4,5,6,7], k = 2" do
        nums = [1,2,3,4,5,6,7]
        k = 2

        rotate(nums, k)
        expect(nums).to eq([6,7,1,2,3,4,5])
    end

    it "nums = [1,2,3,4,5,6,7], k = 3" do
        nums = [1,2,3,4,5,6,7]
        k = 3

        rotate(nums, k)
        expect(nums).to eq([5,6,7,1,2,3,4])
    end

    it "nums = [-1,-100,3,99], k = 1" do
        nums = [-1,-100,3,99]
        k = 1

        rotate(nums, k)
        expect(nums).to eq([99,-1,-100,3])
    end

    it "nums = [-1,-100,3,99], k = 2" do
        nums = [-1,-100,3,99]
        k = 2

        rotate(nums, k)
        expect(nums).to eq([3,99,-1,-100])
    end
end