From d9b5a89702f737cd156a71c57c324a225e3f234b Mon Sep 17 00:00:00 2001
From: inga-lovinde <52715130+inga-lovinde@users.noreply.github.com>
Date: Tue, 15 Dec 2020 11:56:06 +0100
Subject: [PATCH] Solution for day 14 part 2

---
 day14-hard/Cargo.toml  | 11 +++++
 day14-hard/src/main.rs | 97 ++++++++++++++++++++++++++++++++++++++++++
 day14/src/main.rs      |  1 -
 3 files changed, 108 insertions(+), 1 deletion(-)
 create mode 100644 day14-hard/Cargo.toml
 create mode 100644 day14-hard/src/main.rs

diff --git a/day14-hard/Cargo.toml b/day14-hard/Cargo.toml
new file mode 100644
index 0000000..2a96f68
--- /dev/null
+++ b/day14-hard/Cargo.toml
@@ -0,0 +1,11 @@
+[package]
+name = "day14-hard"
+version = "0.1.0"
+authors = ["inga-lovinde <52715130+inga-lovinde@users.noreply.github.com>"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+lazy_static = "1.4.0"
+regex = "1"
diff --git a/day14-hard/src/main.rs b/day14-hard/src/main.rs
new file mode 100644
index 0000000..334d6bf
--- /dev/null
+++ b/day14-hard/src/main.rs
@@ -0,0 +1,97 @@
+use std::collections::HashMap;
+use std::error::Error;
+use std::io::{self, BufRead};
+use std::str::FromStr;
+
+#[macro_use] extern crate lazy_static;
+use regex::Regex;
+
+#[derive(Clone, Copy, Debug)]
+struct Mask {
+    pub bypass: u64,
+    pub floating: u64,
+    pub ones: u64,
+}
+
+#[derive(Clone, Copy, Debug)]
+enum Instruction {
+    SetMask(Mask),
+    SetValue{ address: u64, value: u128 },
+}
+
+impl FromStr for Instruction {
+    type Err = Box<dyn Error>;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        lazy_static! {
+            static ref MASK_RE: Regex = Regex::new(r"^mask\s*=\s*([01X]+)$").unwrap();
+            static ref MEM_RE: Regex = Regex::new(r"^mem\[(\d+)\]\s*=\s*(\d+)$").unwrap();
+        }
+
+        match (MASK_RE.captures(s), MEM_RE.captures(s)) {
+            (Some(mask_captures), None) => Ok(Self::SetMask(Mask {
+                bypass: u64::from_str_radix(&mask_captures[1].replace("1", "X").replace("0", "1").replace("X", "0"), 2)?,
+                floating: u64::from_str_radix(&mask_captures[1].replace("1", "0").replace("X", "1"), 2)?,
+                ones: u64::from_str_radix(&mask_captures[1].replace("X", "0"), 2)?,
+            })),
+            (None, Some(mem_re)) => Ok(Self::SetValue {
+                address: mem_re[1].parse()?,
+                value: mem_re[2].parse()?,
+            }),
+            _ => Err(Box::from("Wrong string format")),
+        }
+    }
+}
+
+struct ProgramState {
+    mask: Mask,
+    memory: HashMap<u64, u128>,
+}
+
+impl ProgramState {
+    pub fn new() -> ProgramState {
+        ProgramState {
+            mask: Mask {
+                bypass: !0,
+                floating: 0,
+                ones: 0,
+            },
+            memory: HashMap::new(),
+        }
+    }
+
+    pub fn apply_instruction(&mut self, instruction: Instruction) -> () {
+        match instruction {
+            Instruction::SetMask(mask) => self.mask = mask,
+            Instruction::SetValue{ address, value } => {
+                let address_min = (address & self.mask.bypass) | self.mask.ones;
+                let address_max = address_min | self.mask.floating;
+                for i in address_min..=address_max { // insanely slow, could be optimized, but I'm lazy :(
+                    if (i & address_min) == address_min && (i & address_max) == i {
+                        self.memory.insert(i, value);
+                        println!("Inserting {} into {}", value, i);
+                    }
+                }
+            }
+        }
+    }
+
+    pub fn get_sum(&self) -> u128 {
+        self.memory.values().sum()
+    }
+}
+
+fn main() {
+    let stdin = io::stdin();
+    let instructions: Vec<_> = stdin.lock().lines().into_iter()
+        .map(|line| line.unwrap().parse::<Instruction>().unwrap())
+        .collect();
+
+    let mut program_state = ProgramState::new();
+    for instruction in instructions {
+        program_state.apply_instruction(instruction);
+        println!("Processed instruction");
+    }
+
+    println!("{}", program_state.get_sum());
+}
diff --git a/day14/src/main.rs b/day14/src/main.rs
index e93f847..66e8da7 100644
--- a/day14/src/main.rs
+++ b/day14/src/main.rs
@@ -1,4 +1,3 @@
-use std::collections::HashSet;
 use std::io::{self, BufRead};
 use std::error::Error;
 use std::str::FromStr;