blob: 82bccd1cae379e0120dd6d68c959b73f062a8668 (
plain)
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
|
use crate::io::{Value, TWO};
use std::ops::{Index, IndexMut};
pub fn encode<X: Index<usize, Output = Value> + IndexMut<usize, Output = Value>>(
size: usize,
a: &mut X,
b: &mut X,
) {
let mut k = size;
while k != 1 {
k /= 2;
for i in 0..k {
let x = a[i * 2];
let y = a[i * 2 + 1];
b[i] = x + y;
b[k + i] = x - y;
}
for i in 0..k {
a[i] = b[i]
}
}
}
pub fn decode<X: Index<usize, Output = Value> + IndexMut<usize, Output = Value>>(
size: usize,
a: &mut X,
b: &mut X,
) {
let mut k = 1;
while k != size {
for i in 0..k {
let avr = a[i] / TWO;
let spread = a[i + k] / TWO;
b[i * 2] = avr + spread;
b[i * 2 + 1] = avr - spread;
}
k *= 2;
for i in 0..k {
a[i] = b[i]
}
}
}
|
