1 files changed, 46 insertions, 0 deletions
diff --git a/19/py/d16.py b/19/py/d16.py
new file mode 100644
index 0000000..93b52d2
--- /dev/null
+++ b/19/py/d16.py
@@ -0,0 +1,46 @@
+def do(input, phases=100, repeats=1):
+    nums = []
+    for i in range(repeats):
+        nums += [int(x) for x in input[0].strip()]
+
+    for phase in range(phases):
+        #print(phase)
+        new_list = []
+        for i in range(len(nums)):  # position of number to calculate
+            new_num = 0
+            for k in range(len(nums)):
+                mod = (k+1) % (4*(i+1))
+                if mod >= i + 1 and mod < 2*i + 2:
+                    new_num += nums[k]
+                elif mod >= 3*i + 3:
+                    new_num -= nums[k]
+            new_list.append(abs(new_num) % 10)
+        nums = new_list
+    return "".join([str(n) for n in nums[:8]])
+
+def pt1(input):
+    return do(input, phases=100, repeats=1)
+
+def pt2(input, phases=100, repeats=10000):
+    offset = int(input[0][:7])
+    nums = []
+    for i in range(repeats):
+        nums += [int(x) for x in input[0].strip()]
+    nums = nums[offset:]
+    for phase in range(phases):
+        #print(phase)
+        nums = nums[::-1]
+        new_nums = []
+        n = sum(nums)
+        while len(nums) != 0:
+            new_nums.append(abs(n) % 10)
+            n -= nums.pop()
+        nums = new_nums
+    return "".join([str(n) for n in nums[:8]])
+
+if __name__ == "__main__":
+    input = open("../input/16", "r").readlines()
+    ans1 = pt1(input)
+    ans2 = pt2(input)
+    print(ans1)
+    print(ans2)