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# Problem 26: Reciprocal cycles
# https://projecteuler.net/problem=26
recur <- function(x, output = "") {
# Prepare variable
if (x == 0) return(NaN)
if (x == 1) return(0)
x <- floor(abs(x))
# Initiate vectors to store decimals and remainders
dec <- vector()
rem <- vector()
# Initiate values
i <- 1
r <- 10
rem <- r
# Long division
repeat {
dec[i] <- floor(r / x)
r <- 10 * (r %% x)
# Test wether the number is terminating or repeating
if (r == 0 | r %in% rem) break
rem[i + 1] <- r
i <- i + 1
}
# Determine number of recurring digits
rep <- ifelse(r != 0, length(rem) - which(r == rem) + 1, 0)
# Output
if (output == "len")
return(rep)
else {
if (rep != 0) {
if (rep == length(dec))
l <- "("
else
l <- c(dec[1:(length(dec) - rep)], "(")
dec <- c(l, dec[(length(dec) - rep + 1):length(dec)], ")")
}
return(paste0("0.", paste0(dec, collapse = "", sep = "")))
}
}
A051626 <- sapply(1:1000, recur, "len")
answer <- which.max(A051626)
print(answer)
recur(998001, "len")
recur(998001)