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#!/usr/bin/awk
#
# See ../README.md
#
#
# Run as: awk -f ch-2.awk < input-file
#
#
# Read input from standard input, assuming one exercise per line.
# Each line consists of a string $S, and a pattern $T, separated
# by whitespace.
#
#
# Recursively count matches:
# - If either the string or the pattern is empty, there are no matches.
# - Else, + count the matches if we don't match at the first character
# if the string.
# + if the first character of the string equals the first
# character of the pattern:
# o add 1 if the pattern is just one character long
# o else, add the number of matches starting from the
# then next character in the string, and the next
# character in the pattern.
#
#
# Note that we do not have lexical variables in AWK, so we're
# using a global count variable.
#
function matches (string, pattern) {
if (length (string) == 0 || length (pattern) == 0) {
return 0
}
matches(substr (string, 2), pattern)
if (substr (string, 1, 1) == substr (pattern, 1, 1)) {
if (length (pattern) == 1) {
count ++
}
else {
matches(substr (string, 2), substr (pattern, 2))
}
}
}
{
count = 0
matches($1, $2)
print count
}
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