add new solutions

solutions/0/q67/solution.go

@@ -0,0 +1,28 @@
+package q67
+
+func toDigit(byt byte) uint8  { return byt - '0' }
+func toByte(digit uint8) byte { return '0' + digit }
+
+func addBinary(a string, b string) string {
+	lenA, lenB := len(a), len(b)
+	ret := make([]byte, max(lenA, lenB)+1)
+	var carry uint8
+	for i := range ret {
+		d := carry
+		if i < lenA {
+			d += toDigit(a[lenA-i-1])
+		}
+		if i < lenB {
+			d += toDigit(b[lenB-i-1])
+		}
+		carry = d / 2
+		ret[len(ret)-i-1] = toByte(d % 2)
+	}
+
+	if ret[0] != '1' {
+		return string(ret[1:])
+	}
+	return string(ret)
+}
+
+var _ = addBinary