Just another update

Task/Text-processing-Max-licenses-in-use/Go/text-processing-max-licenses-in-use.go

@@ -1,60 +1,60 @@
 package main
 
 import (
-    "bufio"
-    "fmt"
-    "io"
-    "os"
-    "bytes"
+	"bufio"
+	"bytes"
+	"fmt"
+	"log"
+	"os"
 )
 
-var fn = "mlijobs.txt"
+const (
+	filename   = "mlijobs.txt"
+	inoutField = 1
+	timeField  = 3
+	numFields  = 7
+)
 
 func main() {
-    f, err := os.Open(fn)
-    if err != nil {
-        fmt.Println(err)
-        return
-    }
-    defer f.Close()
-    var ml, out int
-    var mlTimes []string
-    in := []byte("IN")
-    for lr := bufio.NewReader(f); ; {
-        line, pref, err := lr.ReadLine()
-        if err == io.EOF {
-            break
-        }
-        if err != nil {
-            fmt.Println(err)
-            return
-        }
-        if pref {
-            fmt.Println("Unexpected long line.")
-            return
-        }
-        f := bytes.Fields(line)
-        if len(f) != 7 {
-            fmt.Println("unexpected format,", len(f), "fields.")
-            return
-        }
-        if bytes.Equal(f[1], in) {
-            out--
-            continue
-        }
-        out++
-        if out == ml {
-            mlTimes = append(mlTimes, string(f[3]))
-            continue
-        }
-        if out > ml {
-            ml = out
-            mlTimes = append(mlTimes[:0], string(f[3]))
-        }
-    }
-    fmt.Println("max licenses:", ml)
-    fmt.Println("at:")
-    for _, t := range mlTimes {
-        fmt.Println(" ", t)
-    }
+	file, err := os.Open(filename)
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer file.Close()
+	var ml, out int
+	var mlTimes []string
+	in := []byte("IN")
+	s := bufio.NewScanner(file)
+	for s.Scan() {
+		f := bytes.Fields(s.Bytes())
+		if len(f) != numFields {
+			log.Fatal("unexpected format,", len(f), "fields.")
+		}
+		if bytes.Equal(f[inoutField], in) {
+			out--
+			if out < 0 {
+				log.Fatalf("negative license use at %s", f[timeField])
+			}
+			continue
+		}
+		out++
+		if out < ml {
+			continue
+		}
+
+		if out > ml {
+			ml = out
+			mlTimes = mlTimes[:0]
+		}
+		mlTimes = append(mlTimes, string(f[timeField]))
+	}
+	if err = s.Err(); err != nil {
+		log.Fatal(err)
+	}
+
+	fmt.Println("max licenses:", ml)
+	fmt.Println("at:")
+	for _, t := range mlTimes {
+		fmt.Println(" ", t)
+	}
 }