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-rw-r--r--challenge-113/abigail/lua/ch-1.lua46
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diff --git a/challenge-113/abigail/lua/ch-1.lua b/challenge-113/abigail/lua/ch-1.lua
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+#!/opt/local/bin/lua
+
+--
+-- See ../README.md
+--
+
+--
+-- Run as: lua ch-1.lua < input-file
+--
+
+--
+-- For a description of the algorithm, and the proof why this is correct:
+-- https://abigail.github.io/HTML/Perl-Weekly-Challenge/week-113-1.html
+--
+
+local gcds = {1, 2, 1, 2, 5, 2, 1, 2, 1}
+
+for line in io . lines () do
+ local _, _, N, D = line : find ("([0-9]+)%s+([0-9])")
+ N = tonumber (N)
+ D = tonumber (D)
+ if D == 0
+ then if N >= 100 or N % 10 == 0
+ then print (1)
+ else print (0)
+ end
+ goto end_loop
+ end
+
+ if N >= D * 10
+ then print (1)
+ goto end_loop
+ end
+
+ for i = 0, D / gcds [D] - 1
+ do local T = N - 10 * i - D
+ if T >= 0 and T % D == 0
+ then print (1)
+ goto end_loop
+ end
+ end
+
+ print (0)
+
+ ::end_loop::
+end