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#!/usr/bin/awk
#
# See ../README.md
#
#
# Run as: awk -f ch-2.awk < input-file
#
function substrings (n, m, prefix, max, fc, tail, n_prefix) {
if (length (n) == 0) {
#
# End of recursion
#
return prefix > -1 && \
prefix < max && \
prefix % m == 0 ? 1 : 0
}
fc = substr (n, 1, 1)
tail = substr (n, 2)
n_prefix = 10 * (prefix == -1 ? 0 : prefix) + fc
return substrings(tail, m, n_prefix, max) + \
substrings(tail, m, prefix, max)
}
{
print (substrings($1, $2, -1, $1))
}
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