Add solution for day 16

AoC2021/code/AoC16.py

@@ -0,0 +1,68 @@
+#!/usr/bin/env python3
+
+import sys
+from bitstring import BitArray
+from operator import mul
+from functools import reduce
+
+def parse_packet(packet, s, np=100000000, length=1000000000):
+    nex = s
+    end = s+length-1
+    bv = 0
+    numbers = []
+    while np > 0 and nex < min(len(packet)+1,end):
+        if (len(packet[nex:end+1]) == 0 or int(''.join(packet[nex:end+1]),2) == 0 or int(''.join(packet[nex:]),2) == 0):
+            if length < 1000000000: nex = end+1
+            break
+        v = int(''.join(packet[nex:nex+3]),2)
+        bv += v
+        t = int(''.join(packet[nex+3:nex+6]),2)
+        nex += 6       
+        if t == 4:
+            num = []
+            while (n := packet[nex]) == '1':
+                num.append(list(packet[nex+1:nex+5]))
+                nex += 5
+            num.append(list(packet[nex+1:nex+5]))
+            nex += 5
+            i = int(''.join([''.join(n) for n in num]),2)
+            numbers.append(i)
+        else:
+            I = packet[nex]
+            nex += 1
+            if I == '1': 
+                l = int(''.join(packet[nex:nex+11]),2)
+                nex += 11
+                b, nex, numbs = parse_packet(packet, nex, np=l)
+                bv += b
+            elif I == '0': 
+                l = int(''.join(packet[nex:nex+15]),2)
+                nex += 15
+                b, nex, numbs = parse_packet(packet, nex, length=l)
+                bv += b
+            if t == 0: numbers.append(sum(numbs))
+            elif t == 1: numbers.append(reduce(mul, numbs, 1))
+            elif t == 2: numbers.append(min(numbs))
+            elif t == 3: numbers.append(max(numbs))
+            elif t == 5: numbers.append(int(numbs[0] > numbs[1]))
+            elif t == 6: numbers.append(int(numbs[0] < numbs[1]))
+            elif t == 7: numbers.append(int(numbs[0] == numbs[1]))
+
+        np -= 1
+    return bv, nex, numbers
+
+if __name__ == '__main__':
+    hexa = [list(line.strip('\n')) for line in open(sys.argv[1])]
+    bits = [list(BitArray(hex=c).bin) for c in hexa[0]]
+    bits = [b  for l in bits for b in l]
+
+    bv, _, num = parse_packet(bits,0,np=1)
+
+    # challenge 1
+    res1 = str(bv)
+    print("challenge 1:" + "\n" +  res1 + "\n")
+
+    # challenge 2
+    res2 = str(num[0])
+    print("challenge 2:" + "\n" +  res2 + "\n")
+