valid_parenthesis.rs

impl Solution {
    pub fn is_valid(s: String) -> bool {
        let mut stack = Vec::new();
        let match_of = |c: char| -> char {
            match c {
                ')' => '(',
                '}' => '{',
                ']' => '[',
                _ => panic!("Invalid closing bracket"),
            }
        };
        for ch in s.chars() {
            match ch {
                '(' | '{' | '[' => stack.push(ch),
                closing => {
                    if let Some(closing_bracket) = stack.pop() {
                        if closing_bracket != match_of(closing) {
                            return false;
                        }
                    } else {
                        return false;
                    }
                }
            }
        }
        stack.is_empty()
    }
}