45 lines
1.0 KiB
Rust
45 lines
1.0 KiB
Rust
pub fn roman_to_int(string: String) -> i32 {
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let mut characters = string.chars().peekable();
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let mut number = 0;
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while let Some(character) = characters.next() {
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let value = match character {
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'I' => 1,
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'V' => 5,
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'X' => 10,
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'L' => 50,
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'C' => 100,
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'D' => 500,
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'M' => 1000,
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_ => panic!("Unknown character: {character}"),
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};
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if let Some(next) = characters.peek() {
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let subtract = match next {
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'V' | 'X' if character == 'I' => true,
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'L' | 'C' if character == 'X' => true,
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'D' | 'M' if character == 'C' => true,
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_ => false,
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};
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if subtract {
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number -= value;
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continue;
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}
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}
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number += value;
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}
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number
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}
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#[test]
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fn test_roman_to_integer() {
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assert_eq!(roman_to_int("III".to_string()), 3);
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assert_eq!(roman_to_int("LVIII".to_string()), 58);
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assert_eq!(roman_to_int("MCMXCIV".to_string()), 1994);
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assert_eq!(roman_to_int("XX".to_string()), 20);
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assert_eq!(roman_to_int("DCXXI".to_string()), 621);
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}
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