Rust HashMap macro

roman-to-integers.rs

// https://leetcode.com/problems/roman-to-integer

use lazy_static::lazy_static;
use std::collections::HashMap;

macro_rules! map {
    ($( $t: expr),*) => {{
         let mut map = HashMap::new();
         $( map.insert($t.0, $t.1); )*
         map
    }}
}

lazy_static! {
    static ref LETTERS: HashMap<char, i32> = map!(
        ('I', 1),
        ('V', 5),
        ('X', 10),
        ('L', 50),
        ('C', 100),
        ('D', 500),
        ('M', 1000),
        ('a', 4),
        ('b', 9),
        ('c', 40),
        ('d', 90),
        ('e', 400),
        ('f', 900)
    );
}

impl Solution {
    pub fn roman_to_int(s: String) -> i32 {
        let s = s.as_str();
        let s = s.replace("CM", "f");
        let s = s.replace("CD", "e");
        let s = s.replace("XC", "d");
        let s = s.replace("XL", "c");
        let s = s.replace("IX", "b");
        let s = s.replace("IV", "a");
        
        s.chars().fold(0, |acc, c| acc +  LETTERS.get(&c).unwrap())
    }
}

rust-map-macro.rs

use std::collections::HashMap;

macro_rules! hashmap {
    ($( $key: expr => $val: expr ),*) => {{
         let mut map = HashMap::new();
         $( map.insert($key, $val); )*
         map
    }}
}

macro_rules! map {
    ($( $t: expr),*) => {{
         let mut map = HashMap::new();
         $( map.insert($t.0, $t.1); )*
         map
    }}
}

fn get_map() -> HashMap<char, i32> {
    hashmap!('a' => 1, 'b' => 2)
}


fn main() {
    let m1 = hashmap!('a' => 1, 'b' => 2);
    println!("{:?}", m1);
    
    let m1 = map!(('a', 1), ('b', 2));
    println!("{:?}", m1);
}