updated format to look like gopl.io format

ch1/dup/dup2.go

@@ -0,0 +1,37 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"log"
+	"os"
+)
+
+func main() {
+	counts := make(map[string]int)
+	file := os.Args[1:]
+	if len(file) == 0 {
+		countLines(os.Stdin, counts)
+	} else {
+		for _, i := range file {
+			f, err := os.Open(i)
+			if err != nil {
+				log.Print(err)
+			}
+			countLines(f, counts)
+			f.Close()
+		}
+	}
+	for lines, n := range counts {
+		if n > 1 {
+			fmt.Printf("%d\t%s\n", n, lines)
+		}
+	}
+}
+
+func countLines(f *os.File, counts map[string]int) {
+	input := bufio.NewScanner(f)
+	for input.Scan() {
+		counts[input.Text()]++
+	}
+}