add day-04 + benchmarks

day-04/internal/util/util.go

@@ -0,0 +1,21 @@
+package util
+
+import (
+	"bufio"
+	"io"
+)
+
+func ReadLines(r io.Reader) ([]string, error) {
+	lines := []string{}
+
+	scanner := bufio.NewScanner(r)
+	for scanner.Scan() {
+		lines = append(lines, scanner.Text())
+	}
+
+	if err := scanner.Err(); err != nil {
+		return []string{}, err
+	}
+
+	return lines, nil
+}