competitive_library/structure/
skew_heap.rs

1//! Skew Heap
2
3use std::mem::swap;
4#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord)]
5pub struct Heap<T: Ord + Clone> {
6    pub value: T,
7    pub left: Option<Box<Heap<T>>>,
8    pub right: Option<Box<Heap<T>>>,
9}
10
11impl<T: Ord + Clone> Heap<T> {
12    pub fn new(value: T) -> Option<Box<Heap<T>>> {
13        Some(Box::new(Heap {
14            value,
15            left: None,
16            right: None,
17        }))
18    }
19}
20#[derive(Default, Clone)]
21pub struct SkewHeap<T: Ord + Clone> {
22    node: Option<Box<Heap<T>>>,
23}
24impl<T: Ord + Clone> SkewHeap<T> {
25    pub fn new() -> Self {
26        Self { node: None }
27    }
28
29    #[inline]
30    pub fn push(&mut self, value: T) {
31        SkewHeap::merge(&mut self.node, Heap::new(value));
32    }
33    #[inline]
34    pub fn top(&self) -> Option<T> {
35        Some(self.node.as_ref()?.value.clone())
36    }
37    #[inline]
38    pub fn pop(&mut self) -> Option<T> {
39        let value = self.top()?;
40
41        let (mut left, right) = {
42            let mut tmp = self.node.take().unwrap();
43            (tmp.left.take(), tmp.right.take())
44        };
45        SkewHeap::merge(&mut left, right);
46        swap(&mut self.node, &mut left);
47
48        Some(value)
49    }
50
51    #[inline]
52    pub fn merge(a: &mut Option<Box<Heap<T>>>, mut b: Option<Box<Heap<T>>>) {
53        if a.is_none() {
54            swap(a, &mut b);
55            return;
56        }
57        if b.is_none() {
58            return;
59        }
60        if a > &mut b {
61            swap(a, &mut b);
62        }
63        SkewHeap::merge(&mut a.as_mut().unwrap().right, b);
64
65        let tmp = a.as_mut().unwrap();
66        swap(&mut tmp.left, &mut tmp.right);
67    }
68}
69
70#[cfg(test)]
71mod tests {
72    use super::*;
73    #[test]
74    fn test_heap() {
75        let mut a = vec![SkewHeap::new(); 5];
76
77        for i in 0..30 {
78            a[i % 5].push(i);
79        }
80
81        for (i, e) in a.iter().enumerate() {
82            assert_eq!(e.top().unwrap(), i);
83        }
84
85        for i in 1..5 {
86            let buff = a[i].node.take();
87            SkewHeap::merge(&mut a[0].node, buff);
88        }
89
90        for i in 0..30 {
91            assert_eq!(a[0].pop().unwrap(), i);
92        }
93    }
94}
competitive_library/structure/skew_heap.rs

competitive_library/structure/
skew_heap.rs
