From b189ba4c821cfb08690930575027b877294aeec9 Mon Sep 17 00:00:00 2001
From: Jessie Zhang <zhang_jessie2017@outlook.com>
Date: Fri, 28 Sep 2018 09:02:58 -0700
Subject: [PATCH] reverse_sentence

---
 lib/reverse_sentence.rb | 51 ++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 50 insertions(+), 1 deletion(-)

diff --git a/lib/reverse_sentence.rb b/lib/reverse_sentence.rb
index af2a20b..16ae0f0 100644
--- a/lib/reverse_sentence.rb
+++ b/lib/reverse_sentence.rb
@@ -1,4 +1,53 @@
 # A method to reverse the words in a sentence, in place.
+require 'pry'
+
+def partial_reverse(my_string, start_index, end_index)
+   i = start_index
+   j = end_index
+
+   while i < j
+     temp = my_string[i]
+     my_string[i] = my_string[j]
+     my_string[j] = temp
+     i += 1
+     j -= 1
+   end
+   return
+end
+
+def reverse_words(my_words)
+  return if my_words.nil? || my_words.length == 0
+
+  i=0
+  length = my_words.length
+  while i < length
+    while my_words[i] == " " && i < length
+      i += 1
+    end
+
+    start_index = i
+
+    while my_words[i] != " " && i < length
+      i += 1
+    end
+
+    end_index = i-1
+
+    partial_reverse(my_words, start_index, end_index)
+  end
+
+  return
+end
+
 def reverse_sentence(my_sentence)
-  raise NotImplementedError
+  return if my_sentence.nil? || my_sentence.length == 0
+
+  i = 0
+  length = my_sentence.length
+  j = length - 1
+
+  partial_reverse(my_sentence, i, j)
+  reverse_words(my_sentence)
+
+  return my_sentence
 end