Use sets for both answers and some clean up

03/c.py

@@ -6,17 +6,14 @@ tot = 0
 tot2 = 0
 
 priorities = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
-commons = ''
 
 rucksacks = f.read().splitlines()
-rucksacks2 = []
+f.close()
 
 for data in rucksacks:
     left = data[:len(data)//2]
     right = data[len(data)//2:]
-
-    common = ''.join(set(left).intersection(right))
-
+    common = ''.join(set(left) & set(right))
     tot = tot + priorities.rfind(common)+1
 
 print("First answer: " + str(tot))
@@ -25,9 +22,8 @@ start = 0
 end = len(rucksacks)
 step = 3
 for i in range(start, end, step):
-
     three = rucksacks[i:i+step]
-    common = set(three[0]) & set(three[1]) & set(three[2])
-    tot2 = tot2 + priorities.rfind(''.join(common))+1
+    common = ''.join(set(three[0]) & set(three[1]) & set(three[2]))
+    tot2 = tot2 + priorities.rfind(common)+1
 
 print("Second answer: " + str(tot2))