Merge pull request #66 from vaskoz/day28

Day28

README.md

@@ -41,3 +41,4 @@ problems from
 * [Day 25](https://github.com/vaskoz/dailycodingproblem-go/issues/59)
 * [Day 26](https://github.com/vaskoz/dailycodingproblem-go/issues/61)
 * [Day 27](https://github.com/vaskoz/dailycodingproblem-go/issues/63)
+* [Day 28](https://github.com/vaskoz/dailycodingproblem-go/issues/65)

day28/problem.go

@@ -0,0 +1,51 @@
+package day28
+
+import (
+	"fmt"
+	"strings"
+)
+
+// Justify returns a slice of justified strings.
+func Justify(words []string, k int) []string {
+	var line, result []string
+	var lineLength int
+	for i := 0; i < len(words); i++ {
+		word := words[i]
+		if lineLength+len(word)+len(line) <= k {
+			lineLength += len(word)
+			line = append(line, word)
+		} else {
+			result = append(result, buildLine(line, k, lineLength))
+			line = line[:0] // truncate
+			lineLength = 0
+			i-- // retry this word
+		}
+	}
+	last := buildLine(line, k, lineLength)
+	if last != "" {
+		result = append(result, last)
+	}
+	return result
+}
+
+func buildLine(line []string, k, lineLength int) string {
+	if len(line) == 1 {
+		spaces := k - lineLength
+		return fmt.Sprintf("%s%s", line[0], strings.Repeat(" ", spaces))
+	}
+	var sb strings.Builder
+	minimumSpaces := (k - lineLength) / len(line)
+	extraSpaces := k - lineLength - ((len(line) - 1) * minimumSpaces)
+	for i, word := range line {
+		sb.WriteString(word)
+		if i == len(line)-1 {
+			break
+		}
+		spaces := minimumSpaces
+		if i < extraSpaces {
+			spaces++
+		}
+		sb.WriteString(strings.Repeat(" ", spaces))
+	}
+	return sb.String()
+}

day28/problem_test.go

@@ -0,0 +1,35 @@
+package day28
+
+import (
+	"reflect"
+	"testing"
+)
+
+var testcases = []struct {
+	words    []string
+	k        int
+	expected []string
+}{
+	{[]string{"bird"},
+		6,
+		[]string{"bird  "}},
+	{[]string{"the", "quick", "brown", "fox", "jumps", "over", "the", "lazy", "dog"},
+		16,
+		[]string{"the  quick brown", "fox  jumps  over", "the   lazy   dog"}},
+}
+
+func TestJustify(t *testing.T) {
+	for _, tc := range testcases {
+		if result := Justify(tc.words, tc.k); !reflect.DeepEqual(tc.expected, result) {
+			t.Errorf("Expected %v but got %v", tc.expected, result)
+		}
+	}
+}
+
+func BenchmarkJustify(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		for _, tc := range testcases {
+			Justify(tc.words, tc.k)
+		}
+	}
+}