day 3 in rust

2024/day-3-rust/src/main.rs

@@ -0,0 +1,68 @@
+use std::fs;
+use std::io;
+extern crate regex; // Add regex crate to your Cargo.toml
+use regex::Regex;
+
+
+fn main() -> io::Result<()> {
+    let pattern = r"^mul\(\d{1,3},\d{1,3}\)$";
+    let file_contents: String = fs::read_to_string("medium.txt")?;
+    let length_of_string = file_contents.len(); 
+    let re = Regex::new(pattern).unwrap();
+    let mut total: u32 = 0;
+    let mut total2: u32 = 0;
+    let mut enabled: bool = true;
+
+    for i in 0..length_of_string {
+        let substring = &file_contents[i..i+1];
+        if substring == "d" {
+            //println!("{},{}",&file_contents[i..i+3],&file_contents[i..i+6]);
+            if &file_contents[i..i+4] == "do()" {
+                enabled = true;
+            }
+            else if &file_contents[i..i+7] == "don't()" {
+                enabled = false;
+            }
+        }
+        else if substring == "m" {
+            let mut closed_bracket_position = 0;
+            for j in i+3..length_of_string {
+                let next_closed_bracket = &file_contents[j..j+1];
+                if next_closed_bracket == ")" {
+                    closed_bracket_position = j;
+                    break;
+                }
+                // check it's reached the end of string
+            }
+            let string_to_check = &file_contents[i..closed_bracket_position+1];
+            //println!("String to check is {}",&file_contents[i..closed_bracket_position+1]);
+            if re.is_match(string_to_check) {
+                //println!("{} is VALID!!!", string_to_check);
+                let mut comma_position = 5;
+                for j in 5..string_to_check.len() {
+                    if &string_to_check[j..j+1] == "," {
+                        comma_position = j;
+                    }
+                }
+                let number1: &Result<u32, _> = &string_to_check[4..comma_position].parse();
+                let number2: &Result<u32, _> = &string_to_check[comma_position+1..string_to_check.len()-1].parse();
+                match (number1, number2) {
+                    (Ok(n1), Ok(n2)) => {
+                        let result = n1 * n2;
+                        //println!("Multiplication result: {}", result);
+                        total = total + result;
+                        if enabled == true {
+                            total2 = total2 + result;
+                        }
+                    },
+                    _ => {
+                        //println!("One or both of the values are invalid.");
+                    }
+                }
+            }
+        }
+    }
+    println!("Part 1 total is: {}", total);
+    println!("Part 2 total is: {}", total2);
+    Ok(())
+}