Day 15

2023/day15/code.py

@@ -0,0 +1,47 @@
+#!/usr/bin/env python3
+
+import sys, re
+
+
+def HASH(string):
+    res = 0
+    for a in string:
+        res += ord(a)
+        res = res * 17 % 256
+    return res
+
+
+if __name__ == '__main__':
+    instr = open(sys.argv[1]).read().strip('\n').split(',')
+
+    # challenge 1
+    res1 = sum([HASH(a) for a in instr])
+    
+    boxes = {}
+    for i in instr:
+        label, op, focus = re.findall(r'(\w+)(\-|\=)(\d*)', i)[0]
+        box = HASH(label)
+        if not box in boxes.keys(): boxes[box] = []
+        present = boxes[box]
+        if op == '=':
+            for i, lens in enumerate(present):
+                if lens[0] == label: present[i] = (label, int(focus)) 
+            if not (label, int(focus)) in present: present.append((label, int(focus)))
+        elif op == '-':
+            for i, lens in enumerate(present):
+                if lens[0] == label:
+                    present.remove(lens)
+                    break
+
+    res2 = 0
+    for b, lenses in boxes.items():
+        for i,l in enumerate(lenses):
+            res2 += (b+1) * (i+1) * l[1]
+
+    res1 = str(res1)
+    print(f"challenge 1:\n{res1}\n")
+
+    # challenge 2
+    res2 = str(res2)
+    print(f"challenge 2:\n{res2}\n")
+