Function leetcode_for_rust::cd0020_valid_parentheses::is_valid2

pub fn is_valid2(s: String) -> bool

Solutions

Approach 1: Stacks

• Time complexity: O(n)

• Space complexity: O(n)

use std::collections::HashMap;

impl Solution {
    pub fn is_valid2(s: String) -> bool {
        let mut paren_stack = vec![];
        let mut paren_map: HashMap<char, char> = HashMap::new();
        paren_map.insert(')', '(');
        paren_map.insert('}', '{');
        paren_map.insert(']', '[');

        for ch in s.chars() {
            match ch {
                '(' | '{' | '[' => paren_stack.push(ch),
                _ => {
                    let expected = *paren_map.get(&ch).unwrap();
                    let actual = paren_stack.pop().unwrap();
                    if expected != actual {
                        return false;
                    }
                }
            }
        }

        paren_stack.is_empty()
    }
}