Day 3: Part 2

main.py

@@ -1,28 +1,30 @@
 batteries = []
 
 with open("day3/input.txt") as file:
-    lines = file.readlines()
-    for line in lines:
-        line = line.strip("\n")
-        data = []
-        for joltage in line:
-            data.append(int(joltage))
-        batteries.append(data)
+    for line in file:
+        batteries.append([int(c) for c in line.strip()])
 
-joltageSum = 0
+
+def max_12_digit_number(digits):
+    target_len = 12
+    to_remove = len(digits) - target_len
+    stack = []
+
+    for d in digits:
+        while stack and to_remove > 0 and stack[-1] < d:
+            stack.pop()
+            to_remove -= 1
+        stack.append(d)
+
+    # Falls noch nicht genug entfernt wurde (am Ende nur große Zahlen)
+    return stack[:target_len]
+
+
+total = 0
 
 for bank in batteries:
-    tenthPlace = max(bank)
-    onethPlace = 0
-    indexOfMax = bank.index(tenthPlace)
-    if(indexOfMax == len(bank)-1):
-        onethPlace = tenthPlace
-        tenthPlace = max(bank[:-1])
-    else:
-        onethPlace = max(bank[indexOfMax+1::])
-    
-    joltageBank = int(f"{tenthPlace}{onethPlace}")
-    print(f"Bank {batteries.index(bank)+1} joltage is {joltageBank}")
-    joltageSum+=joltageBank
+    best_digits = max_12_digit_number(bank)
+    joltage = int("".join(map(str, best_digits)))
+    total += joltage
 
-print(joltageSum)
+print(total)