Complete exercises

string_manipulation.rb

@@ -1,23 +1,93 @@
 # A method to reverse a string in place.
 def string_reverse(my_string)
-  puts "NOT IMPLEMENTED"
+  j = my_string.length - 1
+  i = 0
+  while i < j
+    temp = my_string[i]
+    my_string[i] = my_string[j]
+    my_string[j] = temp
+    i += 1
+    j -= 1
+  end
+  return my_string
 end
 
 # A method to reverse each word in a sentence, in place.
 def reverse_words(my_words)
-  puts "NOT IMPLEMENTED"
+  length = my_words.length
+  first_i = 0
+
+  length.times do |i|
+    if my_words[i] == ' ' || i == length - 1
+      last_i = i - 1
+      if last_i + 1 == length - 1
+        last_i = i
+      end
+      while first_i < last_i
+        temp = my_words[first_i]
+        my_words[first_i] = my_words[last_i]
+        my_words[last_i] = temp
+        first_i += 1
+        last_i -= 1
+      end
+      first_i = i + 1
+    end
+  end
+  return my_words
 end
 
 # A method to reverse the words in a sentence, in place.
 def reverse_sentence(my_sentence)
-  puts "NOT IMPLEMENTED"
+  length = my_sentence.length
+
+  j = my_sentence.length - 1
+  i = 0
+  while i < j
+    temp = my_sentence[i]
+    my_sentence[i] = my_sentence[j]
+    my_sentence[j] = temp
+    i += 1
+    j -= 1
+  end
+
+  first_i = 0
+  length.times do |index|
+    if my_sentence[index] == ' ' || index == length - 1
+      last_i = index - 1
+      if last_i + 1 == length - 1
+        last_i = index
+      end
+      while first_i < last_i
+        temp = my_sentence[first_i]
+        my_sentence[first_i] = my_sentence[last_i]
+        my_sentence[last_i] = temp
+        first_i += 1
+        last_i -= 1
+      end
+      first_i = index + 1
+    end
+  end
+  return my_sentence
 end
 
 # A method to check if the input string is a palindrome.
 # Return true if the string is a palindrome. Return false otherwise.
 def palindrome_check(my_phrase)
-  puts "NOT IMPLEMENTED"
-  return true
+  length = my_phrase.length
+
+  if length == 0
+    return false
+  end
+
+  i = 0
+  j = -1
+  while i < -j
+    if my_phrase[i] != my_phrase[j]
+      return false
+    else
+      return true
+    end
+  end
 end
 
 # A method that updates the string by replacing consecutive repeating characters
@@ -44,6 +114,7 @@ def encode_repeating(my_string)
 puts "Original: #{my_words}"
 reversed_words = "I nac eb na  reenigne"
 reverse_words(my_words)
+
 if my_words == reversed_words
   puts "Words reversed correctly. Reversed words: #{reversed_words}"
 else