day 9

1 files changed, 49 insertions, 0 deletions

diff --git a/20/py/d09.py b/20/py/d09.py
new file mode 100644
index 0000000..4379039
--- /dev/null
+++ b/20/py/d09.py
@@ -0,0 +1,49 @@
+#!/usr/bin/env python3
+import sys
+from collections import deque
+
+
+def intify(_in):
+    return list(int(n.strip()) for n in _in)
+
+
+def pt1(_in):
+    valid = []
+    for i in range(25):
+        for j in range(i+1, 25):
+            valid.append(_in[i] + _in[j])
+    for i in range(25, len(_in)):
+        if _in[i] not in valid:
+            return _in[i]
+        valid = valid[24:]
+        offset = 0
+        for j in range(1, 25)[::-1]:
+            valid.insert(offset, _in[i - j] + _in[i])
+            offset += j
+
+
+def pt2(_in):
+    invalid = pt1(_in)
+
+    i, s, nums = 0, 0, deque()
+    while s != invalid:
+        if s < invalid:
+            # add
+            s += _in[i]
+            nums.append(_in[i])
+            i += 1
+        else:
+            # pop
+            s -= nums[0]
+            nums.popleft()
+    return min(nums) + max(nums)
+
+
+if __name__ == "__main__":
+    if len(sys.argv) > 1:
+        input = open(sys.argv[1], "r").readlines()
+    else:
+        input = open("../input/09", "r").readlines()
+    input = intify(input)
+    print(pt1(input))
+    print(pt2(input))