merge([1, 3, 5, 7], [2, 4, 6, 8]) / \ merge([3, 5, 7], [2, 4, 6, 8]) merge([1, 3, 5, 7], [4, 6, 8]) / \ / \ merge([5, 7], [2, 4, 6, 8]) merge([3, 5, 7], [6, 8]) merge([1, 3, 5], [4, 6, 8]) merge([1, 3, 5, 7], [8]) / \ / \ / \ merge([7], [2, 4, 6, 8]) merge([5, 7], [6, 8]) merge([3, 5], [4, 6, 8]) merge([1, 3, 5], [6, 8]) merge([1, 3, 5, 7], []) / \ / \ / \ [7] [2, 4, 6, 8] [5, 7] [6, 8] [3, 5] [4, 6, 8] / \ / \ / \ / \ / \ [] [2, 4, 6, 8] [5] [7] [6] [8] [3] [5] [4] [6, 8] / \ / \ / \ / \ / \ / \ / \ [] [] [] [] [] [] [] [] [] [] [] [] [] [] [] [] []