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The original was posted on /r/rust by /u/omagdy7 on 2023-08-23 17:17:55.

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I am doing some leetcode and solved the same problem in both C++ and Rust and the 2 solutions are pretty much the same but the C++ solution is 100x the Rust one I am definitely doing something wrong here but can’t put my finger on it. Here are the two solutions:

C++:

class Solution {
public:

    bool helper(string &s, string &t, unordered_map &mp) {
            for (int i = 0; i < s.size(); i++) {
                if (mp.find(s[i]) != mp.end()) {
                    auto tmp = mp[s[i]];
                    mp[s[i]] = t[i];
                    if (tmp != mp[s[i]]) {
                        return false;
                    }
                } else {
                    mp[s[i]] = t[i];
                }
            }
            return true;
    }

    bool isIsomorphic(string s, string t) {
        if (s.size() != t.size()) return false;
        unordered_map mp;
        if (unordered_set(s.begin(), s.end()).size() <= unordered_set(t.begin(), t.end()).size()) {
            return helper(s, t, mp);
        } else {
            return helper(t, s, mp);
        }
    }
};

Rust

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

pub fn helper(s : &String, t: &String, mp : &mut HashMap) -> bool {
    for i in 0..s.len() {
        if let Some(&ele) = mp.get(&s.chars().nth(i).unwrap()) {
            if ele != t.chars().nth(i).unwrap() {
                return false;
            }
        } else {
            mp.insert(s.chars().nth(i).unwrap(), t.chars().nth(i).unwrap());
        }
    }
    return true;
}

impl Solution {
    pub fn is_isomorphic(s: String, t: String) -> bool {
        if s.len() != t.len() {
            return false;
        }

        let mut mp : HashMap = HashMap::new();

        if s.chars().collect::>().len() < t.chars().collect::>().len() {
            helper(&s, &t, &mut mp)
        } else {
            helper(&t, &s, &mut mp)
        }
    }
}

Edit: Thanks a lot guys for the all the input and tips and tricks