Rosetta Code

Power set: Difference between revisions

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Power set (view source)

Revision as of 01:35, 27 January 2020

1 byte removed ,  4 years ago
m
→‎Non-recursive version: Fix syntax
Line 3,193:
This method is much faster than a recursive method, though the speed is still O(2^n).
 
<lang R>powerset =<- function(set){
ps =<- list()
ps[[1]] =<- numeric() #Start with the empty set.
for(element in set){ #For each element in the set, take all subsets
temp =<- vector(mode="list",length=length(ps)) #currently in "ps" and create new subsets (in "temp")
for(subset in 1:length(ps)){ #by adding "element" to each of them.
temp[[subset]] = c(ps[[subset]],element)
}
ps= <- c(ps,temp) #Add the additional subsets ("temp") to "ps".
}
return(ps)
}
 
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