Alternative Node.js solution for week 137, part 1

1 files changed, 37 insertions, 0 deletions

diff --git a/challenge-137/abigail/node/ch-1a.js b/challenge-137/abigail/node/ch-1a.js
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+++ b/challenge-137/abigail/node/ch-1a.js
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+#!/usr/local/bin/node
+
+//
+// See ../README.md
+//
+
+//
+// Run as: node ch-1a.js < input-file
+//
+
+let SUNDAY    = 0
+let MONDAY    = 1
+let TUESDAY   = 2
+let WEDNESDAY = 3
+let THURSDAY  = 4
+let FRIDAY    = 5
+let SATURDAY  = 6
+
+function doomsday (year) {
+    let anchor   = [TUESDAY, SUNDAY, FRIDAY, WEDNESDAY]
+                   [Math . floor (year / 100) % 4]
+    let y        = year % 100
+    let doomsday = ((Math . floor  (y / 12) + (y % 12) +
+                     Math . floor ((y % 12) / 4)) + anchor) % 7
+    return (doomsday)
+}
+
+function is_leap (year) {
+    return ((year % 400 == 0) || (year % 4 == 0 && year % 100 != 0))
+}
+
+for (year = 1900; year <= 2100; year ++) {
+    let dec_31 = (doomsday (year) + 31 - 12) % 7
+    if (dec_31 == THURSDAY || dec_31 == FRIDAY && is_leap (year)) {
+        console . log (year)
+    }
+}