// Copyright © 2018 Inanc Gumus // Learn Go Programming Course // License: https://creativecommons.org/licenses/by-nc-sa/4.0/ // // For more tutorials : https://learngoprogramming.com // In-person training : https://www.linkedin.com/in/inancgumus/ // Follow me on twitter: https://twitter.com/inancgumus package main import ( "bufio" "fmt" "os" "sort" "strconv" "strings" ) func main() { var ( sum map[string]int // total visits per domain domains []string // unique domain names total int // total visits to all domains lines int // number of parsed lines (for the error messages) ) sum = make(map[string]int) // Scan the standard-in line by line in := bufio.NewScanner(os.Stdin) for in.Scan() { lines++ // Parse the fields fields := strings.Fields(in.Text()) if len(fields) != 2 { fmt.Printf("wrong input: %v (line #%d)\n", fields, lines) return } domain := fields[0] // Sum the total visits per domain visits, err := strconv.Atoi(fields[1]) if visits < 0 || err != nil { fmt.Printf("wrong input: %q (line #%d)\n", fields[1], lines) return } // Collect the unique domains if _, ok := sum[domain]; !ok { domains = append(domains, domain) } // Keep track of total and per domain visits total += visits sum[domain] += visits } // Print the visits per domain sort.Strings(domains) fmt.Printf("%-30s %10s\n", "DOMAIN", "VISITS") fmt.Println(strings.Repeat("-", 45)) for _, domain := range domains { visits := sum[domain] fmt.Printf("%-30s %10d\n", domain, visits) } // Print the total visits for all domains fmt.Printf("\n%-30s %10d\n", "TOTAL", total) // Let's handle the error if err := in.Err(); err != nil { fmt.Println("> Err:", err) } }