From 729a5b30379935a406bd5692d7fdad0b69c2fb29 Mon Sep 17 00:00:00 2001
From: Kyle Isom <kyle@imap.cc>
Date: Tue, 13 Nov 2018 09:18:07 -0800
Subject: [PATCH] Start shipping problem.

---
 misc/planeleg.py | 67 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 67 insertions(+)
 create mode 100755 misc/planeleg.py

diff --git a/misc/planeleg.py b/misc/planeleg.py
new file mode 100755
index 0000000..d879689
--- /dev/null
+++ b/misc/planeleg.py
@@ -0,0 +1,67 @@
+#!/usr/bin/env python3
+
+DAYS = ['M', 'T', 'W', 'R', 'F']
+
+TEST_SET = [
+    ('M', 'PDX', 'SEA'),
+    ('T', 'PDX', 'SFO'),
+    ('T', 'SEA', 'DEN'),
+    ('W', 'DEN', 'PDX'),
+    ('R', 'PDX', 'DEN'),
+    ('F', 'DEN', 'JFK')
+]
+
+EXPECTED = [
+    [('M', 'PDX', 'SEA'), ('T', 'SEA', 'DEN'), ('W', 'DEN', 'PDX'), ('R', 'PDX', 'DEN'), ('F', 'DEN', 'JFK')],
+    [('T', 'PDX', 'SFO')]
+]
+
+def self_check():
+    print('self_check days: ', end="")
+    test_days()
+
+    trip = build_matches(TEST_SET[0], TEST_SET[1:])
+    print('leg: {}, trips: {}'.format(TEST_SET[0], trip))
+
+def test_days():
+    try:
+        assert(next_day('M') == 'T')
+        assert(next_day('T') == 'W')
+        assert(next_day('W') == 'R')
+        assert(next_day('R') == 'F')
+        assert(next_day('F') == 'M')
+    except:
+        print('FAILED')
+        raise
+    print('OK')
+
+def next_day(day):
+    assert(day in DAYS)
+    return DAYS[(DAYS.index(day) + 1) % len(DAYS)]
+
+def match_leg(leg1, leg2):
+    (day1, origin1, destination1) = leg1
+    (day2, origin2, destination2) = leg2
+    if day2 == next_day(day1) and origin2 == destination1:
+        return True
+    return False
+
+def find_next_match(leg, candidates):
+    for candidate in candidates:
+        if match_leg(leg, candidate):
+            return candidate
+    return None
+
+def build_matches(leg, candidates):
+    trip = []
+    cset = set(candidates)
+    while True:
+        candidate = find_next_match(leg, cset)
+        if not candidate:
+            return trip, cset
+        trip.append(candidate)
+        cset.remove(candidate)
+        leg = candidate
+
+if __name__ == '__main__':
+    self_check()
\ No newline at end of file