From 3983a072b0505d9ed0f1c4bb5314cd115e5ede89 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Juan=20Jos=C3=A9=20Guti=C3=A9rrez=20de=20Quevedo=20P=C3=A9?=
 =?UTF-8?q?rez?= <juanjo@gutierrezdequevedo.com>
Date: Sun, 13 Dec 2020 22:06:40 +0100
Subject: [PATCH] add day 13

---
 13/1.py   |  9 +++++++++
 13/2.py   | 31 +++++++++++++++++++++++++++++++
 13/einput |  2 ++
 13/input  |  2 ++
 4 files changed, 44 insertions(+)
 create mode 100644 13/1.py
 create mode 100644 13/2.py
 create mode 100644 13/einput
 create mode 100644 13/input

diff --git a/13/1.py b/13/1.py
new file mode 100644
index 0000000..1ec0350
--- /dev/null
+++ b/13/1.py
@@ -0,0 +1,9 @@
+with open("input") as f:
+    content = [x.strip() for x in f]
+
+timestamp = int(content[0])
+buses = [int(x) for x in content[1].split(",") if x != "x"]
+next_deps = [((int(timestamp / x) + 1) * x) - timestamp for x in buses]
+next_dep = min(next_deps)
+next_bus = buses[next_deps.index(next_dep)]
+print(next_bus * next_dep)
diff --git a/13/2.py b/13/2.py
new file mode 100644
index 0000000..1593b3f
--- /dev/null
+++ b/13/2.py
@@ -0,0 +1,31 @@
+def is_correct_timestamp(buses, timestamp):
+    for pos, bus in buses:
+        if (timestamp + pos) % bus != 0:
+                return False
+    return True
+
+# t -> initial timestamp
+# dx -> dx
+def doa2(buses, t, dx):
+    timestamp = t
+    while True:
+        if is_correct_timestamp(buses, timestamp):
+            break
+        timestamp += dx
+
+    return timestamp
+
+with open("input") as f:
+    content = [x.strip() for x in f]
+
+splcont = content[1].split(",")
+tbuses = zip(range(len(splcont)), [int(x) if x != "x" else None for x in splcont])
+buses = list(filter(lambda x: x[1] != None, tbuses))
+
+dx = buses[0][1]
+t = buses[0][0]
+for i in range(1, len(buses)):
+    t = doa2(buses[i:i+2], t, dx)
+    dx *= buses[i][1]
+
+print(t)
diff --git a/13/einput b/13/einput
new file mode 100644
index 0000000..e473080
--- /dev/null
+++ b/13/einput
@@ -0,0 +1,2 @@
+939
+7,13,x,x,59,x,31,19
\ No newline at end of file
diff --git a/13/input b/13/input
new file mode 100644
index 0000000..0a5136f
--- /dev/null
+++ b/13/input
@@ -0,0 +1,2 @@
+1000507
+29,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,37,x,x,x,x,x,631,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,13,19,x,x,x,23,x,x,x,x,x,x,x,383,x,x,x,x,x,x,x,x,x,41,x,x,x,x,x,x,17