1. A method of decoding a video on a decoder, the method comprising: obtaining, from a bitstream, split information for a coding unit; when the split information indicates a non-split for the coding unit, obtaining, from the bitstream, a skip flag for the coding unit which indicates whether a prediction mode for the coding unit is a skip mode; when the skip flag indicates the skip mode, obtaining, from the bitstream, a merge index of the coding unit indicating one block among a candidate block group of the coding unit, the candidate block group of the coding unit including one or more blocks among three or more neighboring blocks of the coding unit; when the skip flag indicates a non-skip mode, obtaining, from the bitstream, a partition type and merge information of a partition; when the partition type is obtained from the bitstream, determining one or more partitions, including the partition, from the coding unit based on the partition type; and when the merge information of the partition indicates a merge mode, obtaining, from the bitstream, a merge index of the partition indicating one block among a candidate block group of the partition, the merge information of the partition indicating whether the partition is decoded in the merge mode and the candidate block group of the partition including one or more blocks among three or more neighboring blocks of the partition, wherein: when the split information indicates a split for a current depth, the coding unit of the current depth is split into four rectangular coding units of a lower depth, independently from neighboring coding units, when the split information indicates a non-split of the current depth, the one or more partitions are obtained from the coding unit of the current depth and one or more transformation units are obtained from the coding unit of the current depth, and when a left partition and a right partition are determined as the one or more partitions of the coding unit and the partition is the right partition, the candidate block group of the partition does not include the left partition.