import 2021

2021/day6/day6.py

@@ -0,0 +1,26 @@
+from collections import defaultdict, Counter
+
+def calculate_fishes(inp, days):
+    fishes = Counter(inp)
+    for day in range(days):
+        fishes_new = defaultdict(int)
+        for fish, cnt in fishes.items():
+            if fish == 0:
+                fishes_new[8] += cnt
+                fishes_new[6] += cnt
+            else:
+                fishes_new[fish - 1] += cnt
+        fishes = fishes_new
+    return sum(fishes.values())
+    
+
+def main(infile):
+    with open(infile) as f:
+        inp = [int(x) for x in f.readline().split(",")]
+    res = calculate_fishes(inp, 80)
+    print(f"Part 1, {res}")
+    res = calculate_fishes(inp, 256)
+    print(f"Part 2, {res}")
+
+if __name__ == "__main__":
+    main("input.txt")