day 3, part 1 in awk and compat part 2

d03/part1.awk

@@ -0,0 +1,12 @@
+{
+	split(substr($0,1,length($0)/2),arr,"")
+	r = substr($0,1+length($0)/2)
+	for (a in arr) {
+		c = arr[a]
+		if (index(r,c)>0) {
+			comm = c
+		}
+	}
+	S += index("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ", comm)
+}
+END {print S}

d03/part2.awk

@@ -1,24 +1,12 @@
-NR %3 == 1 { split($0, arr, "") 
+NR%3==1 {split($0,arr,"");for(a in arr){A[arr[a]]=1}}
-	for (a in arr) {
+NR%3==2 {split($0,arr,"");for(a in arr){B[arr[a]]=1}}
-		A[arr[a]]=1
-	}
-}
-NR %3 == 2 { split($0, arr, "") 
-	for (a in arr) {
-		B[arr[a]]=1
-	}
-}
 NR%3==0 {
 	split($0,arr,"")
 	for (a in arr) {
 		c = arr[a]
-		if ((c in A) && (c in B)) {
+		if ((c in A)&&(c in B)) {comm = c}
-			comm = c
 	}
-	}
+	S += index("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ", comm)
-	i = index("abcdefghijklmnopqrstuvwxyz", comm)
-	j = index("ABCDEFGHIJKLMNOPQRSTUVWXYZ", comm)+26
-	S += i > 0 ? i : j
 	delete A
 	delete B
 }