add day 13

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)