First commit

Author: OmnicWolf

.gitignore

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+/target

Cargo.lock

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+[package]
+name = "leetcode_rust"
+version = "0.1.0"
+edition = "2021"
+authors = ["Ryo Light <[email protected]>"]
+
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+phf = { version = "0.11.2", features = ["macros"] }

Cargo.toml

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+# Leetcode Solutions in Rust

Readme.md

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+pub mod roman_to_int;
+
+pub fn run() {
+  display_roman_to_int("XIV");
+  display_roman_to_int("XLII");
+}
+
+fn display_roman_to_int(s: &str) {
+  println!("{} -> {}", s, roman_to_int::solve(String::from(s)));
+}

src/easy/mod.rs

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+#![allow(dead_code)]
+
+use phf::phf_map;
+
+/*
+ * Problem: 13. Roman to Integer (Easy)
+ * URL: https://leetcode.com/problems/roman-to-integer/
+ *
+ * Runtime: ? ms (%)
+ * Memory Usage: ? MB (%)
+ */
+
+static ROMAN_NUMERALS_STR: phf::Map<&'static str, i32> = phf_map! {
+  "I" => 1,
+  "V" => 5,
+  "X" => 10,
+  "L" => 50,
+  "C" => 100,
+  "D" => 500,
+  "M" => 1000
+};
+
+static ROMAN_NUMERALS: phf::Map<char, i32> = phf_map! {
+  'I' => 1,
+  'V' => 5,
+  'X' => 10,
+  'L' => 50,
+  'C' => 100,
+  'D' => 500,
+  'M' => 1000
+};
+
+pub fn solve(s: String) -> i32 {
+  let mut result: i32 = 0;
+
+  let mut buf = [0; 1];
+
+  let mut subtract_previous = false;
+
+  for (i, char) in s.chars().enumerate() {
+    let val = ROMAN_NUMERALS_STR.get(char.encode_utf8(&mut buf)).unwrap();
+
+    if subtract_previous {
+      result += val - ROMAN_NUMERALS_STR.get(s.get(i-1..i).unwrap()).unwrap();
+      subtract_previous = false;
+      continue;
+    }
+
+    if i+1 < s.len() && val < ROMAN_NUMERALS_STR.get(s.get(i+1..i+2).unwrap()).unwrap() {
+      subtract_previous = true;
+    } else {
+      result += val;
+    }
+
+  }
+
+  return result;
+} 
+
+const NUMERALS: [(char, u32); 7] = [
+  ('I', 1),
+  ('V', 5),
+  ('X', 10),
+  ('L', 50),
+  ('C', 100),
+  ('D', 500),
+  ('M', 1000),
+];
+
+/*
+    Symbol       Value
+    I             1
+    V             5
+    X             10
+    L             50
+    C             100
+    D             500
+    M             1000
+
+    I can be placed before V (5) and X (10) to make 4 and 9.
+    X can be placed before L (50) and C (100) to make 40 and 90.
+    C can be placed before D (500) and M (1000) to make 400 and 900.
+ */

src/easy/roman_to_int.rs

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+// #![allow(dead_code)]
+
+pub mod easy;
+
+fn main() {
+    easy::run();
+}