dsalgo 0.3.10

A package for Datastructures and Algorithms.
Documentation 
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

//! functionality
//! push arbitrary,
//! pop median
//! find median,

use std::{
    cmp::Reverse,
    collections::BinaryHeap,
};

pub struct MedianQueue<T> {
    low_que: BinaryHeap<T>,
    high_que: BinaryHeap<Reverse<T>>,
}

impl<T: Clone + Ord> MedianQueue<T> {
    pub fn new() -> Self {
        Self { low_que: BinaryHeap::new(), high_que: BinaryHeap::new() }
    }

    pub fn size(&self) -> usize {
        self.low_que.len() + self.high_que.len()
    }

    fn low_to_high(&mut self) {
        self.high_que.push(Reverse(self.low_que.pop().unwrap()));
    }

    fn high_to_low(&mut self) {
        self.low_que.push(self.high_que.pop().unwrap().0);
    }

    fn balance(&self) -> isize {
        self.low_que.len() as isize - self.high_que.len() as isize
    }

    fn rebalance(&mut self) {
        match self.balance() {
            2 => self.low_to_high(),
            -1 => self.high_to_low(),
            0 | 1 => (),
            _ => panic!("cannot be"),
        }

        debug_assert!(self.balance() == 0 || self.balance() == 1);
    }

    pub fn push(
        &mut self,
        x: T,
    ) {
        if self.balance() == 1 {
            self.low_que.push(x);
        } else {
            self.high_que.push(Reverse(x));
        }

        self.rebalance();
    }

    pub fn low(&self) -> Option<&T> {
        self.low_que.peek()
    }

    pub fn high(&self) -> Option<&T> {
        if self.balance() == 1 {
            self.low_que.peek()
        } else if let Some(Reverse(x)) = self.high_que.peek() {
            Some(x)
        } else {
            None
        }
    }

    pub fn pop_low(&mut self) -> Option<T> {
        let v = self.low_que.pop();

        self.rebalance();

        v
    }

    pub fn pop_high(&mut self) -> Option<T> {
        let v = if self.balance() == 1 {
            self.low_que.pop()
        } else if let Some(Reverse(x)) = self.high_que.pop() {
            Some(x)
        } else {
            None
        };

        self.rebalance();

        v
    }
}

#[cfg(test)]

mod tests {

    use super::*;

    #[test]

    fn test() {
        let mut que = MedianQueue::new();

        for i in 0..10 {
            que.push(i);
        }

        assert_eq!(que.size(), 10);

        assert_eq!(que.low(), Some(&4));

        assert_eq!(que.high(), Some(&5));

        assert_eq!(que.pop_low(), Some(4));

        assert_eq!(que.low(), Some(&5));

        assert_eq!(que.high(), Some(&5));

        assert_eq!(que.pop_high(), Some(5));

        assert_eq!(que.low(), Some(&3));

        assert_eq!(que.high(), Some(&6));

        que.push(4);

        assert_eq!(que.low(), Some(&4));

        assert_eq!(que.high(), Some(&4));
    }
}