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Move-to-front algorithm: Difference between revisions
Add Rust implementation
m (→{{header|Factor}}: Remove the need for a swap by changing the order of arguments.) |
(Add Rust implementation) |
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Line 2,188:
[7, 8, 15, 2, 15, 2, 2, 3, 2, 2, 3, 2]
true
</pre>
=={{header|Rust}}==
<lang rust>fn main() {
let examples = vec!["broood", "bananaaa", "hiphophiphop"];
for example in examples {
let encoded = encode(example);
let decoded = decode(&encoded);
println!(
"{} encodes to {:?} decodes to {}",
example, encoded, decoded
);
}
}
fn get_symbols() -> Vec<u8> {
(b'a'..b'z').collect()
}
fn encode(input: &str) -> Vec<usize> {
input
.as_bytes()
.iter()
.fold((Vec::new(), get_symbols()), |(mut o, mut s), x| {
let i = s.iter().position(|c| c == x).unwrap();
let c = s.remove(i);
s.insert(0, c);
o.push(i);
(o, s)
})
.0
}
fn decode(input: &[usize]) -> String {
input
.iter()
.fold((Vec::new(), get_symbols()), |(mut o, mut s), x| {
o.push(s[*x]);
let c = s.remove(*x);
s.insert(0, c);
(o, s)
})
.0
.into_iter()
.map(|c| c as char)
.collect()
}</lang>
{{out}}
<pre>
broood encodes to [1, 17, 15, 0, 0, 5] decodes to broood
bananaaa encodes to [1, 1, 13, 1, 1, 1, 0, 0] decodes to bananaaa
hiphophiphop encodes to [7, 8, 15, 2, 15, 2, 2, 3, 2, 2, 3, 2] decodes to hiphophiphop
</pre>
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