LeetCode 1056. Confusing Number

Problem Statement

Backtrack.

use std::collections::HashMap;

impl Solution {
    pub fn confusing_number(n: i32) -> bool {
        let s = n.to_string();

        let map: HashMap<char, char> = [('1', '1'), ('6', '9'), ('8', '8'), ('9', '6'), ('0','0')]
            .iter().cloned().collect();
        let (mut changed, mut i, mut j) = (false, 0, s.len() - 1);
        while i <= j {
            if !map.contains_key(&s.chars().nth(i).unwrap())
                || !map.contains_key(&s.chars().nth(j).unwrap()) {
                return false;
            }
            if map[&s.chars().nth(i).unwrap()] != s.chars().nth(j).unwrap() {
                changed = true;
            }
            i += 1;
            if j != 0 {
                j -= 1;
            }
        }

        return changed;
    }
}