Split: [7, 4, 0, 9, 2, 3, 8, 6, 5, 1]
       [7, 4, 0, 9, 2] [3, 8, 6, 5, 1]

Split: [7, 4, 0, 9, 2]
       [7, 4] [0, 9, 2]

Split: [7, 4]
       [7] [4]

Merge: [7] [4]
       [4, 7]

Split: [0, 9, 2]
       [0] [9, 2]

Split: [9, 2]
       [9] [2]

Merge: [9] [2]
       [2, 9]

Merge: [0] [2, 9]
       [0, 2, 9]

Merge: [4, 7] [0, 2, 9]
       [0, 2, 4, 7, 9]

Split: [3, 8, 6, 5, 1]
       [3, 8] [6, 5, 1]

Split: [3, 8]
       [3] [8]

Merge: [3] [8]
       [3, 8]

Split: [6, 5, 1]
       [6] [5, 1]

Split: [5, 1]
       [5] [1]

Merge: [5] [1]
       [1, 5]

Merge: [6] [1, 5]
       [1, 5, 6]

Merge: [3, 8] [1, 5, 6]
       [1, 3, 5, 6, 8]

Merge: [0, 2, 4, 7, 9] [1, 3, 5, 6, 8]
       [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]