Day 3 Rust solutions

Author: creideiki

day-03/Cargo.toml

@@ -0,0 +1,15 @@
+[package]
+name = "day-03"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
+regex = "1.11.1"
+
+[[bin]]
+name = "03-1"
+path = "src/03-1.rs"
+
+[[bin]]
+name = "03-2"
+path = "src/03-2.rs"

day-03/src/03-1.rs

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+use std::fs;
+use regex::Regex;
+
+fn main() {
+    let input = fs::read_to_string("../03.input").unwrap();
+    let inst = Regex::new(r"mul\([0-9]+,[0-9]+\)").unwrap();
+
+    let score = inst.find_iter(&input)
+        .map(|m| m.as_str())
+        .map(|m| {
+            let l = m.len();
+            &m[4..l-1]
+        })
+        .map(|m| m.split(",")
+             .map(|num| num.parse::<i64>().unwrap())
+             .collect::<Vec<_>>())
+        .map(|m| m[0] * m[1])
+        .reduce(|a, b| a + b).unwrap();
+
+    println!("{score}");
+}

day-03/src/03-2.rs

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+use std::fs;
+use regex::Regex;
+
+fn main() {
+    let input = fs::read_to_string("../03.input").unwrap();
+    let inst = Regex::new(r"do\(\)|don't\(\)|mul\([0-9]+,[0-9]+\)").unwrap();
+
+    let inst_iter = inst.find_iter(&input)
+        .map(|m| m.as_str());
+
+    let mut enabled = true;
+    let mut sum = 0;
+
+    for inst_str in inst_iter {
+        if inst_str.contains(r"don't()") {
+            enabled = false;
+        } else if inst_str.contains(r"do()") {
+            enabled = true;
+        } else if enabled {
+            let l = inst_str.len();
+            let nums = inst_str[4..l-1]
+                .split(",")
+                .map(|num| num.parse::<i64>().unwrap())
+                .collect::<Vec<_>>();
+            sum += nums[0] * nums[1];
+        }
+    }
+
+    println!("{sum}");
+}