From: Ummon <greg.burri@gmail.com>
Date: Mon, 16 Dec 2019 22:38:26 +0000 (+0100)
Subject: Day 15 part 1
X-Git-Url: http://git.euphorik.ch/index.cgi?a=commitdiff_plain;h=61b1389ce0552c4d0b264ce16393f46dc382b08e;p=advent_of_code_2019.git

Day 15 part 1
---

diff --git a/src/day15.rs b/src/day15.rs
index 8e59e65..5e6b653 100644
--- a/src/day15.rs
+++ b/src/day15.rs
@@ -1,30 +1,100 @@
 use super::intcode;
+use std::iter::FromIterator;
+use std::collections::HashMap;
 
-struct RepairDroid {
+#[derive(Debug, Eq, PartialEq, Copy, Clone)]
+enum LocationState {
+    Unknown,
+    Wall,
+    Visited,
+    DeadEnd,
 }
 
-impl intcode::IO for RepairDroid {
+struct DroidTrackingSystem {
+    board: HashMap<(i32, i32), LocationState>,
+    current_path: Vec<(i32, i32)>,
+    oxygen_found: bool
+}
+
+impl DroidTrackingSystem {
+    fn new() -> DroidTrackingSystem {
+        DroidTrackingSystem {
+            board: HashMap::from_iter(vec![((0, 0), LocationState::Visited)].into_iter()),
+            current_path: vec![(0, 0)],
+            oxygen_found: false
+        }
+    }
+
+    fn current_position(&self) -> (i32, i32) { *self.current_path.last().unwrap() }
+
+    fn positions_around(&self) -> Vec<(i64, (i32, i32))> {
+        let (x, y) = self.current_position();
+        vec![(1, (x, y + 1)), (2, (x, y - 1)), (3, (x - 1, y)), (4, (x + 1, y))]
+    }
+
+    fn get_state(&self, position: (i32, i32)) -> LocationState {
+        match self.board.get(&position) {
+            Some(state) => *state,
+            None => LocationState::Unknown
+        }
+    }
+
+    fn set_state(&mut self, position: (i32, i32), state: LocationState) {
+        self.board.insert(position, state);
+    }
+
+    // 1: north, 2: south, 3: west, 4: est.
+    fn next_movement(&mut self) -> i64 {
+        for (mov, pos) in self.positions_around() {
+            if self.get_state(pos) == LocationState::Unknown {
+                self.current_path.push(pos);
+                return mov
+            }
+        }
+
+        for (mov, pos) in self.positions_around() {
+            if self.get_state(pos) == LocationState::Visited {
+                self.set_state(self.current_position(), LocationState::DeadEnd);
+                self.current_path.pop();
+                return mov
+            }
+        }
+
+        panic!("Droid stuck");
+    }
+
+    // 0: droid hit a wall, 1: droid moved one step, 2: droid moved one step and has found the oxygen system.
+    fn reply_from_droid(&mut self, status: i64) {
+        match status {
+            0 => {
+                self.set_state(self.current_position(), LocationState::Wall);
+                self.current_path.pop();
+            }
+            1 => self.set_state(self.current_position(), LocationState::Visited),
+            2 => self.oxygen_found = true,
+            _ => panic!("Unkown droid status: {}", status)
+        }
+    }
+}
+
+impl intcode::IO for DroidTrackingSystem {
     // May block.
     fn read(&mut self) -> i64 {
-        1
+        self.next_movement()
     }
 
     // Send to the output channel.
     fn write(&mut self, value: i64) {
+        self.reply_from_droid(value);
     }
-}
 
-pub fn shorted_path_to_oxygen(code: &[i64]) -> i32 {
-    0
+    fn halt(&self) -> bool {
+        self.oxygen_found
+    }
 }
 
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    #[test]
-    fn part1_sample_1() {
-
-    }
+pub fn nb_of_movement_to_reach_oxygen(code: &[i64]) -> i32 {
+    let mut dts = DroidTrackingSystem::new();
+    intcode::execute_op_code_with_custom_io(code, &mut dts);
+    dts.current_path.len() as i32 - 1
 }
\ No newline at end of file
diff --git a/src/intcode.rs b/src/intcode.rs
index b1968ac..c2a28df 100644
--- a/src/intcode.rs
+++ b/src/intcode.rs
@@ -8,6 +8,7 @@ enum Mode {
 pub trait IO {
     fn read(&mut self) -> i64;
     fn write(&mut self, value: i64);
+    fn halt(&self) -> bool { false }
 }
 
 struct Buffer {
@@ -98,6 +99,8 @@ pub fn execute_op_code_with_custom_io(code: &[i64], io: &mut dyn IO) {
     };
 
     loop {
+        if io.halt() { break; }
+
         let (op, modes) = read_op_and_modes(code[cursor]);
 
         match op {
diff --git a/src/main.rs b/src/main.rs
index f1cb88d..9b2570d 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -112,8 +112,8 @@ fn day14() -> String {
 }
 
 fn day15() -> String {
-    //let code = common::read_list_of_numbers("data/day15.input", ",");
-    format!("part1: {}, part2: {}", "", "")
+    let code = common::read_list_of_numbers("data/day15.input", ",");
+    format!("part1: {}, part2: {}", day15::nb_of_movement_to_reach_oxygen(&code), "")
 }
 
 fn format_micros(t: u128) -> String {