Day 3

03/main.awk

@@ -0,0 +1,97 @@
+function decimal(b) {
+    dec = 0 # LOL
+    split(b, digits, "")
+    for ( place = 1; place <= length(digits); place++ ) {
+        dec += digits[place] * 2 ** ( length(b) - place )
+    }
+    return dec
+}
+
+function rating(seq_array) {
+digit = 1
+while ( length(seq_array) > 1 ) {
+    tally = 0
+
+# finding most common digit at index
+    for ( item in seq_array ) { 
+
+        tally += substr(seq_array[item],digit,1)
+    
+    }
+
+    if ( tally >= length(seq_array) / 2 ) { choice = 1 }
+    if ( tally < length(seq_array) / 2 ) { choice = 0 }
+    # print "choice was: " choice
+
+# delete non matching items from array
+    for ( item in seq_array ) { 
+
+    # print substr(seq_array[item],digit,1) "---? " digit
+        if ( substr(seq_array[item],digit,1) != choice ) { delete seq_array[item] }
+    
+    }
+
+digit += 1
+# print "index: " digit
+}
+for ( item in seq_array ) { return seq_array[item] }
+
+}
+
+function unrating(seq_array) {
+    digit = 1
+    while ( length(seq_array) > 1 ) {
+        tally = 0
+        for ( item in seq_array ) { 
+            tally += substr(seq_array[item],digit,1)
+        }
+
+        if ( tally >= length(seq_array) / 2 ) { choice = 0 } # trivially reversed
+        if ( tally < length(seq_array) / 2 ) { choice = 1 }
+
+        for ( item in seq_array ) { 
+            if ( substr(seq_array[item],digit,1) != choice ) { delete seq_array[item] }
+        }
+
+        digit += 1
+    }
+for ( item in seq_array ) { return seq_array[item] }
+}
+
+# ---------------------- 
+
+function reductor(num) {
+if ( num == 500 ) { print "WARNING" }
+if ( num < NR / 2 )
+    return 0
+    return 1
+}
+
+function deductor(num) {
+if ( num == 500 ) { print "WARNING" }
+if ( num < NR / 2 )
+    return 1
+    return 0
+}
+BEGIN {
+FS="";
+my_index = 1
+}
+{
+    for ( i = 1; i <= length($0); i++ ) array[i] += $i
+    bin[NR] = $0
+    oxygen[NR] = $0
+    dioxide[NR] = $0
+}
+END {
+    for ( i = 1; i <= length($0); i++ ) {
+
+        gamma = gamma reductor(array[i]) # string append 
+        epsilon = epsilon deductor(array[i]) # good place for ` * 0 ` additive identity?
+        }
+     
+    print decimal(gamma) " * " decimal(epsilon) " = " decimal(gamma) * decimal(epsilon)
+
+    print " ---- problem 2 ---- "
+    print decimal(rating(oxygen)) * decimal(unrating(dioxide)) # 5941884
+}