addBinary

addBinary/addBinary.go

@@ -0,0 +1,76 @@
+package main
+
+import "strings"
+
+func addBinary(a string, b string) string {
+	smaller, bigger, offset := getSmaller(a, b)
+	var resultString strings.Builder
+	carry := 0
+	nextCarry := 0
+
+	for i := len(smaller) - 1; i >= 0; i-- {
+		carry = nextCarry
+		nextCarry = 0
+		if smaller[i] == '1' && bigger[i+offset] == '1' {
+			if carry == 1 {
+				resultString.WriteString("1")
+			} else {
+				resultString.WriteString("0")
+			}
+			nextCarry = 1
+		} else if smaller[i] == '0' && bigger[i+offset] == '0' {
+			if carry == 1 {
+				resultString.WriteString("1")
+			} else {
+				resultString.WriteString("0")
+			}
+		} else {
+			if carry == 1 {
+				resultString.WriteString("0")
+				nextCarry = 1
+			} else {
+				resultString.WriteString("1")
+			}
+		}
+	}
+
+	for i := offset - 1; i >= 0; i-- {
+		carry = nextCarry
+		nextCarry = 0
+		if carry == 1 {
+			if bigger[i] == '1' {
+				resultString.WriteString("0")
+				nextCarry = 1
+			} else {
+				if carry == 1 {
+					resultString.WriteString("1")
+				} else {
+					resultString.WriteString("0")
+				}
+			}
+		} else {
+			resultString.WriteByte(bigger[i])
+		}
+
+	}
+
+	if nextCarry == 1 {
+		resultString.WriteString("1")
+	}
+	var reverse strings.Builder
+	result := resultString.String()
+	for i := resultString.Len() - 1; i >= 0; i-- {
+		reverse.WriteByte(result[i])
+	}
+	return reverse.String()
+}
+
+func getSmaller(a, b string) (string, string, int) {
+	if len(a) < len(b) {
+		offset := len(b) - len(a)
+		return a, b, offset
+	} else {
+		offset := len(a) - len(b)
+		return b, a, offset
+	}
+}

addBinary/addBinary_test.go

@@ -0,0 +1,48 @@
+package main
+
+import "testing"
+
+func TestAddBinary(t *testing.T) {
+	t.Run("11, 1", func(t *testing.T) {
+		s1, s2 := "11", "1"
+		got := addBinary(s1, s2)
+		want := "100"
+
+		if got != want {
+			t.Errorf("got %v, want %v", got, want)
+		}
+	})
+	t.Run("1, 1", func(t *testing.T) {
+		s1, s2 := "1", "1"
+		got := addBinary(s1, s2)
+		want := "10"
+
+		if got != want {
+			t.Errorf("got %v, want %v", got, want)
+		}
+	})
+	t.Run("1010, 1011", func(t *testing.T) {
+		s1, s2 := "1010", "1011"
+		got := addBinary(s1, s2)
+		want := "10101"
+
+		if got != want {
+			t.Errorf("got %v, want %v", got, want)
+		}
+	})
+
+	t.Run("HUGE", func(t *testing.T) {
+
+		//24847893154024981730169397005
+		s1 := "10100000100100110110010000010101111011011001101110111111111101000000101111001110001111100001101"
+		//526700554598729746900966573811
+		s2 := "110101001011101110001111100110001010100001101011101010000011011011001011101111001100000011011110011"
+		got := addBinary(s1, s2)
+		//551548447752754728631135970816
+		want := "110111101100010011000101110110100000011101000101011001000011011000001100011110011010010011000000000"
+
+		if got != want {
+			t.Errorf("got %v, want %v", got, want)
+		}
+	})
+}