72 lines
1.6 KiB
Rust
72 lines
1.6 KiB
Rust
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pub fn longest_common_prefix(strings: Vec<String>) -> String {
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// Sort the strings ascending by length.
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let mut strings = strings.clone();
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strings.sort_by(|a, b| a.len().cmp(&b.len()));
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// Then grab the shortest string.
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let shortest_string = match strings.first() {
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Some(string) => string,
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None => return String::new(),
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};
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// The shortest string must be the maximum possible prefix, so start with it.
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let mut prefix = shortest_string.clone();
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// Then loop over the shortest string's length and check if every string in
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// the list starts with the prefix, and if they don't, pop the last character
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// from the prefix.
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for _ in 0..shortest_string.len() {
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// If we find a prefix that all strings start with, we've found the longest
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// common one.
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if strings.iter().all(|string| string.starts_with(&prefix)) {
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break;
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} else {
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prefix.pop();
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}
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}
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// If by the end there is no longest common prefix, the prefix will be an
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// empty string.
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prefix
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}
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#[test]
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fn test_longest_common_prefix() {
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assert_eq!(
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longest_common_prefix(vec![
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"doggo".to_string(),
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"doggie".to_string(),
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"dog".to_string(),
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]),
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"dog"
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);
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assert_eq!(
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longest_common_prefix(vec![
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"flower".to_string(),
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"flow".to_string(),
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"flight".to_string(),
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]),
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"fl"
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);
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assert_eq!(
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longest_common_prefix(vec![
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"dog".to_string(),
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"racecar".to_string(),
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"car".to_string(),
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]),
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""
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);
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assert_eq!(
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longest_common_prefix(vec![
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"dog".to_string(),
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"racecar".to_string(),
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"car".to_string(),
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"".to_string()
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]),
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""
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);
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}
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