// For more tutorials: https://blog.learngoprogramming.com // // Copyright © 2018 Inanc Gumus // Learn Go Programming Course // License: https://creativecommons.org/licenses/by-nc-sa/4.0/ // package main import ( "bufio" "fmt" "os" "sort" "strconv" "strings" ) // visit stores metrics for a domain type visit struct { domain string count int // add more metrics if needed } // parser keep tracks of the parsing type parser struct { sum map[string]visit // metrics per domain domains []string // unique domain names total int // total visits for all domains lines int // number of parsed lines (for the error messages) } func main() { p := parser{sum: make(map[string]visit)} // Scan the standard-in line by line in := bufio.NewScanner(os.Stdin) for in.Scan() { p.lines++ // Parse the fields fields := strings.Fields(in.Text()) if len(fields) != 2 { fmt.Printf("wrong input: %v (line #%d)\n", fields, p.lines) return } // 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], p.lines) return } name := fields[0] // Collect the unique domains if _, ok := p.sum[name]; !ok { p.domains = append(p.domains, name) } // Keep track of total and per domain visits p.total += visits // You cannot assign to composite values // p.sum[name].count += visits // create and assign a new copy of `visit` p.sum[name] = visit{ domain: name, count: visits + p.sum[name].count, } } // Print the visits per domain sort.Strings(p.domains) fmt.Printf("%-30s %10s\n", "DOMAIN", "VISITS") fmt.Println(strings.Repeat("-", 45)) for _, name := range p.domains { visits := p.sum[name] fmt.Printf("%-30s %10d\n", name, visits.count) } // Print the total visits for all domains fmt.Printf("\n%-30s %10d\n", "TOTAL", p.total) }