day03/sol.py

@@ -1,26 +1,34 @@
 input = open("input")
-part1 = 0
+t = 0
-part2 = 0
-shift = [0] + [10**i for i in range(12)]
 for line in input:
-    digits = list(line.strip())
+    cells = list(line.strip())
-    # max[n] is the value of the maximal n digit subsequence
+    cells.reverse()
-    max = [0] * 13
+    b = cells[0]
-    # iterate over the digits in least-significant to most-significant order.
+    max = 0
-    # k is the number of digits already processed.
+    for c in cells[1:]:
-    for (k,c) in enumerate(reversed(digits)):
+        j = int(c+b)
-        c = int(c)
+        if j > max:
-        # the maximal n-digit subsequence we can make that starts with the
+            max = j
-        # current digit (c) is equal to the concatenation of c and the
+        if c > b:
-        # maximal (n-1)-digit subsequence.
+            b = c
-        # if that's more than the best value we've seen so far, update max[n].
+    #print(max)
-        # we have to update max in reverse order in order to avoid reusing digits.
+    t += max
+print(t)
+
+
+# Part 2
+
+input = open("input")
+t = 0
+for line in input:
+    cells = list(line.strip())
+    cells.reverse()
+    max = ["0"*i for i in range(12+1)]
+    for (k,c) in enumerate(cells):
         for i in reversed(range(1,min(k+2,len(max)))):
-            joltage = c*shift[i] + max[i-1]
+            j = c+max[i-1]
-            if joltage > max[i]:
+            if j > max[i]:
-                max[i] = joltage
+                max[i] = j
-    #print(max[12])
+    print(max[12])
-    part1 += int(max[2])
+    t += int(max[12])
-    part2 += int(max[12])
+print(t)
-print(part1)
-print(part2)