- Round arrangement: N different elements take r to make a circular arrangement.
Each circular arrangement can be cut from the adjacent position of R to get a different linear arrangement of R, so the number of circular permutations: ans = P (n, R)/R
- Necklace Arrangement: Similar to the round arrangement, but the circular arrangement is flat, so the flip is different, but the necklace is three-dimensional, after flipping although from the side looks like just now, but the actual is the same, so its arrangement of the number equivalent to half of the round arrangement.
- Multiple permutations: n can be repeated elements to arrange, first to repeat the elements of the subscript three-way ..., and then according to the normal n different elements to calculate, and finally divided by the repetition (this should know how to calculate, x Repeat, divided by x!).
Then there is the "Partition method", which is to put n different elements in the X different areas, such as ... Sorry, forget the typical problem model.
However, the idea is that the partitions are the same, and the "multiple arrangement" as to calculate the better, first add the subscript conversion, and then remove the duplicate.
A variety of permutations
