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sumdigits
2009 Dec 19
4
expand.grid game
Dear list,
In a little numbers game, I've hit a performance snag and I'm not sure
how to code this in C.
The game is the following: how many 8-digit numbers have the sum of
their digits equal to 17?
The brute-force answer could be:
maxi <- 9 # digits from 0 to 9
N <- 5 # 8 is too large
test <- 17 # for example's sake
sum(rowSums(do.call(expand.grid, c(list(1:maxi),