40 lines
1.1 KiB
Rust
40 lines
1.1 KiB
Rust
pub fn is_valid(string: String) -> bool {
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// If the input string is of an odd length it cannot be valid, since every
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// opening character must also have a closing one.
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if string.len() % 2 != 0 {
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return false;
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}
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fn get_closing_character(character: char) -> char {
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match character {
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'[' => ']',
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'{' => '}',
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'(' => ')',
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_ => panic!("Invalid input character: {character}"),
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}
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}
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let mut stack = vec![];
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for character in string.chars() {
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match character {
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// For any opening characters, add their counterpart to the stack and move
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// on to the next character in the string.
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'[' | '{' | '(' => stack.push(get_closing_character(character)),
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// For any other characters, get the most recent character we've seen and
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// if it doesn't equal the expected closing character then the string is
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// invalid.
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_ => {
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if character != stack.pop().unwrap_or_default() {
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return false;
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}
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}
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};
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}
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// After the string has been looped over, if anything is left in the stack the
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// string is invalid.
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stack.len() == 0
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}
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