valid_parentheses.rs

use std::{char, collections::HashMap};

pub struct Solution;

impl Solution {
    // Approach 1 - Brute Force
    pub fn is_valid_brute_force(s: String) -> bool {
        let mut s = s;
        while s.contains("()") || s.contains("[]") || s.contains("{}") {
            s = s.replace("()", "");
            s = s.replace("[]", "");
            s = s.replace("{}", "");
        }
        s.len() == 0
    }

    // Approach 2 - Stack
    pub fn is_valid(s: String) -> bool {
        let mut stack: Vec<char> = Vec::new();
        let map: HashMap<char, char> = HashMap::from([(')', '('), (']', '['), ('}', '{')]);

        for ch in s.chars().into_iter() {
            if map.contains_key(&ch) {
                if stack.len() > 0 && stack.last().unwrap() == map.get(&ch).unwrap() {
                    stack.pop();
                } else {
                    return false;
                }
            } else {
                stack.push(ch);
            }
        }

        stack.len() == 0
    }
}