day 9

r0f1 · r0f1 · commit bd9808c642de · 2020-12-09T09:55:06.000+01:00
diff --git a/README.md b/README.md
@@ -10,7 +10,7 @@
 |[06](https://adventofcode.com/2020/day/6)|Custom Customs|[py](/day06/main.py), [alt](/day06/alt.py)|
 |[07](https://adventofcode.com/2020/day/7)|Handy Haversacks|[py](/day07/main.py), [alt](/day07/alt.py)|
 |[08](https://adventofcode.com/2020/day/8)|Handheld Halting|[py](/day08/main.py)|
-|[09](https://adventofcode.com/2020/day/9)|-|-|
+|[09](https://adventofcode.com/2020/day/9)|Encoding Error|[py](/day09/main.py)|
 |[10](https://adventofcode.com/2020/day/10)|-|-|
 |[11](https://adventofcode.com/2020/day/11)|-|-|
 |[12](https://adventofcode.com/2020/day/12)|-|-|
diff --git a/day09/main.py b/day09/main.py
@@ -0,0 +1,24 @@
+from itertools import combinations
+
+with open("input.txt") as f:
+    numbers = [int(x) for x in f]
+
+p = 25
+for i in range(len(numbers)-p):
+    n = numbers[i+p]
+    for a, b in combinations(numbers[i:i+p], 2):
+        if a+b == n:
+            break
+    else:
+        print(n)
+        break
+
+for i in range(len(numbers)):
+    for j in range(i+1, len(numbers)):
+        elems = numbers[i:j]
+        if sum(elems) == n:
+            print(min(elems)+max(elems))
+            break
+    else:
+        continue
+    break
