ezpz case actually looks ok

main.go

@@ -3,7 +3,6 @@ package main
 import (
 	"bufio"
 	"bytes"
-	"errors"
 	"flag"
 	"io"
 	"os"
@@ -57,14 +56,36 @@ func _readPage(d byte, r *bufio.Reader) ([]byte, error) {
 }
 
 func putPage(b []byte) error {
-	return _putPage(stdout, b)
+	return _putPage(stdout, b, []byte(columnDelimiter)[0], minimumInstances)
 }
 
-func _putPage(w io.Writer, b []byte) error {
+func _putPage(w io.Writer, b []byte, d byte, instances int) error {
+	nonFirstColumn := []byte{}
 	for _, line := range lines(b) {
-		_ = line
+		//line = bytes.TrimSpace(line)
+		i := 0
+		for i < len(line) && line[i] == d {
+			i += 1
 		}
-	return errors.New("not impl")
+		for i < len(line) {
+			j := 0
+			for j+i < len(line) && line[i+j] == d {
+				j += 1
+			}
+			if j >= instances {
+				nonFirstColumn = append(nonFirstColumn, line[i+j:]...)
+				line = line[:i+j]
+				break
+			}
+			i += 1
+		}
+		w.Write(line)
+		w.Write([]byte{'\n'})
+	}
+	if len(nonFirstColumn) > 0 {
+		return _putPage(w, nonFirstColumn, d, instances)
+	}
+	return nil
 }
 
 func lines(b []byte) [][]byte {

main_test.go

@@ -10,7 +10,8 @@ import (
 )
 
 func Test_Main(t *testing.T) {
-	stdin = strings.NewReader("\ta a a\t\tb b b\na a\t\tb b\fc c\td d\nc c\td.")
+	input := "\ta a a\t\tb b b\na a\t\tb b\fc c\td d\nc c\td."
+	stdin = strings.NewReader(input)
 	stdout = bytes.NewBuffer(nil)
 	columnDelimiter = "\t"
 	pageDelimiter = "\f"
@@ -18,7 +19,8 @@ func Test_Main(t *testing.T) {
 	if err := _main(); err != nil {
 		t.Error(err)
 	}
-	t.Errorf("%s", stdout.(*bytes.Buffer).Bytes())
+	t.Logf("input:\n%s", input)
+	t.Errorf("result:\n%s", stdout.(*bytes.Buffer).Bytes())
 }
 
 func TestReadPage(t *testing.T) {