good good study, day day up!

vendor/gopl.io/ch1/dup1/main.go

@@ -0,0 +1,31 @@
+// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+
+// See page 8.
+//!+
+
+// Dup1 prints the text of each line that appears more than
+// once in the standard input, preceded by its count.
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+)
+
+func main() {
+	counts := make(map[string]int)
+	input := bufio.NewScanner(os.Stdin)
+	for input.Scan() {
+		counts[input.Text()]++
+	}
+	// NOTE: ignoring potential errors from input.Err()
+	for line, n := range counts {
+		if n > 1 {
+			fmt.Printf("%d\t%s\n", n, line)
+		}
+	}
+}
+
+//!-