day 8 work and jumbled together

utils/bits/bits.go

@@ -0,0 +1,54 @@
+package bits
+
+func GetBitCount(val int) int {
+	count := 0
+	for val != 0 {
+		count += val & 1
+		val >>= 1
+	}
+
+	return count
+}
+
+// returns the number of matching bits in the two value's binary expression
+func MatchingOnBits(v1 int, v2 int) int {
+	count := 0
+	for v1 != 0 && v2 != 0 {
+		if v1&1 == 1 && v2&1 == 1 {
+			count += 1
+		}
+		v1 >>= 1
+		v2 >>= 1
+	}
+
+	return count
+}
+
+func BitwiseAnd(v1 int, v2 int) int {
+	val := 0
+	for block := 1; v1 != 0 || v2 != 0; block <<= 1 {
+		if v1&1 == 1 || v2&1 == 1 {
+			val += block
+		}
+		if v1 > 0 {
+			v1 >>= 1
+		}
+		if v2 > 0 {
+			v2 >>= 1
+		}
+	}
+	return val
+}
+
+func BitwiseAndA(a ...int) int {
+	total := 0
+	for _, i := range a {
+		total = BitwiseAnd(total, i)
+	}
+
+	return total
+}
+
+func ByBitCount(size int) func(int) bool {
+	return func(val int) bool { return GetBitCount(val) == size }
+}

utils/bits/bits_test.go

@@ -0,0 +1,28 @@
+package bits
+
+import (
+	"AoC2021/utils/assert"
+	"testing"
+)
+
+func TestGetBitCount(t *testing.T) {
+	assert.EqualsInt(t, GetBitCount(0), 0, "should count zero bits")
+	assert.EqualsInt(t, GetBitCount(15), 4, "should count bits")
+	assert.EqualsInt(t, GetBitCount(16), 1, "should not count empty bits")
+}
+func TestMatchingOnBits(t *testing.T) {
+	assert.EqualsInt(t, MatchingOnBits(5 /*101*/, 13 /*1101*/), 2, "should match 2 bits")
+}
+
+func TestBitwiseAnd(t *testing.T) {
+	assert.EqualsInt(t, BitwiseAnd(7 /*111*/, 18 /*10010*/), 23 /*10111*/, "should bitwise add")
+}
+
+func TestBitwiseAndA(t *testing.T) {
+	assert.EqualsInt(t, BitwiseAndA(1, 4, 8, 12), 13 /*1101*/, "should bitwise add lists")
+}
+
+func TestByBitCount(t *testing.T) {
+	twoBitFilter := ByBitCount(2)
+	assert.IsTrue(t, twoBitFilter(17 /*10001*/), "should count bits")
+}