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
use std::default::Default;
use std::slice;
#[derive(Debug, Clone)]
pub struct DStack<I> {
stacks: Vec<I>,
left_head: Option<usize>,
right_head: usize,
}
#[derive(Clone, Copy, PartialEq, Eq, Debug)]
pub enum StackVal<I> {
Enter(I),
Exit(I),
}
impl<I: Default> Default for StackVal<I> {
fn default() -> StackVal<I> {
StackVal::Enter(I::default())
}
}
impl<I> DStack<I> where I: Copy {
pub fn with_capacity(n: usize) -> DStack<I>
where I: Default
{
assert!(n > 1);
DStack {
stacks: vec![I::default(); n],
left_head: None,
right_head: n,
}
}
pub fn capacity(&self) -> usize {
self.stacks.len()
}
pub fn is_left_empty(&self) -> bool {
self.left_head.is_none()
}
pub fn is_right_empty(&self) -> bool {
self.right_head == self.capacity()
}
pub fn push_left(&mut self, value: I) {
let head = self.left_head.map_or(0, |x| x + 1);
assert!(head < self.right_head);
self.stacks[head] = value;
self.left_head = Some(head);
}
pub fn push_right(&mut self, value: I) {
self.right_head -= 1;
if let Some(left_head) = self.left_head {
assert!(self.right_head > left_head);
}
self.stacks[self.right_head] = value;
}
pub fn pop_left(&mut self) -> Option<I> {
match self.left_head {
Some(left_head) => {
let res = self.stacks[left_head];
self.left_head = if left_head > 0 {
Some(left_head - 1)
} else {
None
};
Some(res)
}
None => None,
}
}
pub fn pop_right(&mut self) -> Option<I> {
if self.right_head >= self.stacks.len() {
None
} else {
let res = self.stacks[self.right_head];
self.right_head += 1;
Some(res)
}
}
pub fn len_right(&self) -> usize {
let n = self.stacks.len();
n - self.right_head
}
pub fn clear_right(&mut self) {
self.right_head = self.stacks.len();
}
pub fn clear_left(&mut self) {
self.left_head = None;
}
pub fn iter_right<'a>(&'a self) -> slice::Iter<'a, I> {
self.stacks[self.right_head..].iter()
}
pub fn push_left_on_right(&mut self) {
while let Some(val) = self.pop_left() {
self.push_right(val);
}
}
pub fn push_right_on_left(&mut self) {
while let Some(val) = self.pop_right() {
self.push_left(val);
}
}
}
pub fn extract_stack_val<I>(stack_val: &StackVal<I>) -> &I {
match stack_val {
&StackVal::Enter(ref i) => &i,
&StackVal::Exit(ref i) => &i,
}
}