-
Notifications
You must be signed in to change notification settings - Fork 0
/
lists.rb
executable file
·220 lines (170 loc) · 3.66 KB
/
lists.rb
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
#!/usr/bin/env ruby
class Node
attr_accessor :data, :pointer
def initialize(data, pointer = nil)
self.data = data
pointer = pointer
end
def next?
!self.pointer.nil?
end
end
class TestList
attr_accessor :head
attr_accessor :length
def initialize
self.length = 0
end
def insert_at_front(data)
node = Node.new(data)
if self.head
node.pointer = self.head
self.head = node
else
self.head = node
end
self.length += 1
end
def insert_at_end(data)
node = self.head
while node && node.next? do
node = node.pointer
end
new_node = Node.new(data)
unless self.head
self.head = new_node
else
node.pointer = new_node
end
self.length += 1
end
def xxx
node = self.head
while node && node.next? do
puts node.data
node = node.pointer
end
puts node.data if node
end
end
list = TestList.new
list.insert_at_end(1)
list.insert_at_end(1)
list.insert_at_end(2)
list.insert_at_end(2)
list.insert_at_end(3)
list.insert_at_end(1)
dups = {}
node = list.head
while node && node.next?
dups[node.pointer.data] = true
if dups[node.pointer.data]
node.pointer = node.pointer.pointer
end
node = node.pointer
end
puts 'using a hash'
list.xxx
list = TestList.new
list.insert_at_end(1)
list.insert_at_end(1)
list.insert_at_end(2)
list.insert_at_end(2)
list.insert_at_end(3)
list.insert_at_end(1)
node = list.head
while node && node.next?
runner = node
while runner && runner.next?
if node.data == runner.pointer.data
runner.pointer = runner.pointer.pointer
end
runner = runner.pointer
end
node = node.pointer
end
puts 'using a runner'
list.xxx
list = TestList.new
list.insert_at_end(0)
list.insert_at_end(1)
list.insert_at_end(2)
list.insert_at_end(2)
list.insert_at_end(3)
list.insert_at_end(1)
def kthToLast(node, k)
return 0 unless node
index = kthToLast(node.pointer, k) + 1
puts node.data if k == index
return index
end
puts 'kthToLast'
kthToLast(list.head, 6)
list = TestList.new
list.insert_at_end(3)
list.insert_at_end(5)
list.insert_at_end(8)
list.insert_at_end(5)
list.insert_at_end(10)
list.insert_at_end(2)
list.insert_at_end(1)
def helper(node, pivot, high_list, low_list)
if node
if node.data < pivot
low_list.insert_at_end(node.data)
elsif node.data == pivot
high_list.insert_at_front(node.data)
else
high_list.insert_at_end(node.data)
end
end
end
def partition(node, pivot)
high_list = TestList.new
low_list = TestList.new
while node && node.next?
helper(node, pivot, high_list, low_list)
node = node.pointer
end
helper(node, pivot, high_list, low_list)
result = TestList.new
node = low_list.head
while node
result.insert_at_end(node.data)
node = node.pointer
end
node = high_list.head
while node
result.insert_at_end(node.data)
node = node.pointer
end
puts 'partition result'
result.xxx
end
partition(list.head, 5)
list = TestList.new
list.insert_at_end('r')
list.insert_at_end('a')
list.insert_at_end('d')
list.insert_at_end('a')
list.insert_at_end('r')
list.insert_at_end('r')
class Result
attr_accessor :node, :val
def initialize(node, val)
self.node = node
self.val = val
end
end
def recurse_palindrome(head, length)
return Result.new(head, true) if head.nil? or length <= 0
return Result.new(head.pointer, true) if length == 1
res = recurse_palindrome(head.pointer, length - 2)
return res if res.node.nil? || res.val == false
res.val = (head.data == res.node.data)
res.node = res.node.pointer
res
end
res = recurse_palindrome(list.head, list.length)
puts 'palindrome test'
puts res.val