rust 1337code template

struct Solution {}
impl Solution {
    pub fn is_valid(s: String) -> bool {
        let mut stack: Vec<char> = Vec::new();

        for ch in s.chars() {
            match ch {
                ')' => {
                    if stack.is_empty() || stack.pop().unwrap() != '(' {
                        return false;
                    }
                },
                ']' => {
                    if stack.is_empty() || stack.pop().unwrap() != '[' {
                        return false;
                    }
                },
                '}' => {
                    if stack.is_empty() || stack.pop().unwrap() != '{' {
                        return false;
                    }
                },
                _ => stack.push(ch),
            }
        }

        stack.is_empty()
    }
}

fn main() {
    // Test cases
    let test_cases = vec![
        ("()", true),
        ("()[]{}", true),
        ("(]", false),
        ("([)]", false),
        ("{[]}", true),
        ("", true),
        ("[", false),
        ("]", false),
    ];

    for (i, (input, expected)) in test_cases.iter().enumerate() {
        let result = Solution::is_valid(input.to_string());
        println!("Test {}: '{}' -> {} (expected: {})",
                 i + 1, input, result, expected);
        assert_eq!(result, *expected, "Test failed for input: '{}'", input);
    }

    println!("All tests passed!");
}