From 15117b94410f53379957bd29d3953f7ed96ba774 Mon Sep 17 00:00:00 2001
From: nekineki <nekineki@nekineki.net>
Date: Sat, 7 Dec 2024 21:52:36 +0100
Subject: day07

---
 2024/day07.rs | 78 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 78 insertions(+)
 create mode 100644 2024/day07.rs

(limited to '2024/day07.rs')

diff --git a/2024/day07.rs b/2024/day07.rs
new file mode 100644
index 0000000..e113c27
--- /dev/null
+++ b/2024/day07.rs
@@ -0,0 +1,78 @@
+#![allow(dead_code)]
+#![allow(unused_variables)]
+#![allow(unused_mut)]
+use std::env;
+use std::fs::File;
+use std::io::Read;
+
+fn rec(val: i64, acc: i64, mut eq: Vec<i64>) -> bool {
+    if eq.len() == 0 {
+        if val == acc {
+            return true;
+        } else {
+            return false;
+        }
+    }
+
+    let a = eq.pop().unwrap();
+    return rec(val, acc * a, eq.clone()) || rec(val, acc + a, eq.clone());
+}
+
+fn rec2(val: i64, acc: i64, mut eq: Vec<i64>) -> bool {
+    if eq.len() == 0 {
+        if val == acc {
+            return true;
+        } else {
+            return false;
+        }
+    }
+
+    let a = eq.pop().unwrap();
+    return rec2(val, a + acc * 10_i64.pow(a.checked_ilog10().unwrap() + 1), eq.clone())
+        || rec2(val, acc * a, eq.clone())
+        || rec2(val, acc + a, eq.clone());
+}
+
+fn main() {
+    let args: Vec<String> = env::args().collect();
+    let filename = if args.len() == 1 {
+        "in/".to_owned() + args[0].split('/').last().unwrap() + ".pzl"
+    } else {
+        args[1].clone()
+    };
+    let mut f = File::open(filename).expect("cannot open file");
+    let mut content = String::new();
+    f.read_to_string(&mut content).expect("cannot read file");
+    let lines = content.trim_end().split("\n");
+
+    let mut vals: Vec<i64> = Vec::new();
+    let mut eqs: Vec<Vec<i64>> = Vec::new();
+    for line in lines {
+        let (c, rest) = line.split_once(": ").unwrap();
+        vals.push(c.parse().unwrap());
+        eqs.push(
+            rest.split(" ")
+                .map(|a| a.parse().unwrap())
+                .collect::<Vec<i64>>()
+                .into_iter()
+                .rev()
+                .collect(),
+        );
+    }
+
+    let mut res1 = 0;
+    let mut res2 = 0;
+    for i in 0..eqs.len() {
+        if rec(vals[i], 0, eqs[i].clone()) {
+            res1 += vals[i];
+        }
+        if rec2(vals[i], 0, eqs[i].clone()) {
+            res2 += vals[i];
+        }
+    }
+
+    println!("res1: {}", res1);
+    println!("res2: {}", res2);
+    assert_eq!(res1, 66343330034722);
+    assert_eq!(res2, 637696070419031);
+}
-- 
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