LeetCode 301 Remove Invalid Parentheses

Problem Statement

First attempt on implementing solutions for leetcode problems using Rust. For someone like me with a C++ background,
coding in Rust requires a paradigm change. Move semantics are everywhere, everything has to be explicit, and there are
really not so many similarities of standard libraries between Rust and C++. In any cases, it’s fun to code in Rust,
and I am sure this code can be more Rustified.

use std::collections::HashSet;
use std::collections::VecDeque;

impl Solution {
    pub fn remove_invalid_parentheses(s: String) -> Vec<String> {
        let mut result = Vec::new();
        let mut visited = HashSet::new();
        let mut queue = VecDeque::new();

        fn isParenBalanced(s : &String) -> bool {
            let (mut left, mut right) = (0, 0);
            for c in s.chars() {
                if c == '(' {
                    left = left + 1;
                } else if c == ')' {
                    if left == 0 {
                        return false;
                    }
                    left = left - 1
                }
            }
            return left == 0;
        }
        visited.insert(s.clone());
        queue.push_back(s.clone());

        let mut stop = false;
        while !queue.is_empty() {
            let str = queue.pop_front().unwrap();
            if isParenBalanced(&str) {
                result.push(str.clone());
                stop = true;
            }
            if stop {
                continue;
            }

            for it in str.char_indices() {
                if it.1 != '(' && it.1 != ')' {
                    continue;
                }
                let mut next = str.clone();
                next.remove(it.0);
                if visited.contains(&next) {
                    continue;
                }
                queue.push_back(next.clone());
                visited.insert(next.clone());
            }
        }

        return result;
    }
}