Merge 1bdcaef into e5b10ea

README.md

@@ -121,4 +121,5 @@ problems from
 * [Day 109](https://github.com/vaskoz/dailycodingproblem-go/issues/229)
 * [Day 110](https://github.com/vaskoz/dailycodingproblem-go/issues/231)
 * [Day 111](https://github.com/vaskoz/dailycodingproblem-go/issues/232)
+* [Day 113](https://github.com/vaskoz/dailycodingproblem-go/issues/236)
 * [Day 114](https://github.com/vaskoz/dailycodingproblem-go/issues/237)

day113/problem.go

@@ -0,0 +1,45 @@
+package day113
+
+import (
+	"strings"
+)
+
+// ReverseWords reverses the word position in the string.
+// Runs in O(N) time and requires O(N) additional space.
+func ReverseWords(str string) string {
+	words := strings.Split(str, " ")
+	for i := 0; i < len(words)/2; i++ {
+		words[i], words[len(words)-1-i] = words[len(words)-1-i], words[i]
+	}
+	return strings.Join(words, " ")
+}
+
+// ReverseWordsInPlace reverses the word position in the string.
+// Runs in O(N) time and requires O(1) additional space.
+func ReverseWordsInPlace(str string) string {
+	r := []rune(str)
+	for i := 0; i < len(r)/2; i++ {
+		r[i], r[len(r)-1-i] = r[len(r)-1-i], r[i]
+	}
+	var start, end int
+	for end <= len(r) {
+		if end == len(r) {
+			reverseInPlace(r, start, end)
+		} else if r[end] == ' ' {
+			reverseInPlace(r, start, end)
+			start = end
+			for r[start] == ' ' {
+				start++
+			}
+			end = start - 1
+		}
+		end++
+	}
+	return string(r)
+}
+
+func reverseInPlace(r []rune, start, end int) {
+	for i := start; i < (start+end)/2; i++ {
+		r[i], r[end-1-(i-start)] = r[end-1-(i-start)], r[i]
+	}
+}

day113/problem_test.go

@@ -0,0 +1,44 @@
+package day113
+
+import "testing"
+
+var testcases = []struct {
+	input, expected string
+}{
+	{"hello world here", "here world hello"},
+	{"greetings from colorado", "colorado from greetings"},
+}
+
+func TestReverseWords(t *testing.T) {
+	t.Parallel()
+	for _, tc := range testcases {
+		if result := ReverseWords(tc.input); result != tc.expected {
+			t.Errorf("Expected %v got %v", tc.expected, result)
+		}
+	}
+}
+
+func BenchmarkReverseWords(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		for _, tc := range testcases {
+			ReverseWords(tc.input)
+		}
+	}
+}
+
+func TestReverseWordsInPlace(t *testing.T) {
+	t.Parallel()
+	for _, tc := range testcases {
+		if result := ReverseWordsInPlace(tc.input); result != tc.expected {
+			t.Errorf("Expected %v got %v", tc.expected, result)
+		}
+	}
+}
+
+func BenchmarkReverseWordsInPlace(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		for _, tc := range testcases {
+			ReverseWordsInPlace(tc.input)
+		}
+	}
+}