From 2e7519f3bb769451e3c019d3e95663dff505859f Mon Sep 17 00:00:00 2001
From: Wesley Moore <wes@wezm.net>
Date: Sat, 14 Dec 2019 14:50:19 +1100
Subject: [PATCH] Day 13 part 2

---
 2019/src/bin/day13.rs | 94 +++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 90 insertions(+), 4 deletions(-)

diff --git a/2019/src/bin/day13.rs b/2019/src/bin/day13.rs
index d1fbd1a..2d14033 100644
--- a/2019/src/bin/day13.rs
+++ b/2019/src/bin/day13.rs
@@ -10,10 +10,16 @@ fn main() -> io::Result<()> {
     let input = fs::read_to_string("input/day13.txt")?;
     let program = input::read_separated_line(',', &input)?;
 
+    part1(program.clone());
+    part2(program);
+
+    Ok(())
+}
+
+fn part1(program: Vec<i64>) {
     let mut computer = Computer::new('G', program, vec![], vec![]);
     let res = computer.run(None, None);
     assert_eq!(res, ComputeResult::Halted);
-
     // Process the output
     let final_state: HashMap<_, _> = computer
         .output()
@@ -28,13 +34,93 @@ fn main() -> io::Result<()> {
             )
         })
         .collect();
-
     // How many block tiles are on the screen when the game exits?
     let block_count = final_state
         .iter()
         .filter(|(_point, &tile_id)| tile_id == 2)
         .count();
     println!("Part 1: {}", block_count);
-
-    Ok(())
+}
+
+fn part2(mut program: Vec<i64>) {
+    // Memory address 0 represents the number of quarters that have been inserted; set it to 2 to play for free.
+    program[0] = 2;
+    let mut computer = Computer::new('G', program, vec![], vec![]);
+
+    let mut score = 0;
+    let mut paddle = None;
+    let mut ball = None;
+    let mut width = 0;
+    let mut height = 0;
+    let mut screen = HashMap::new();
+    loop {
+        let res = computer.run(None, None);
+        screen.extend(computer.output().chunks(3).filter_map(|chunk| match chunk {
+            [-1, 0, new_score] => {
+                score = *new_score;
+                None
+            }
+            [x, y, 0] => Some(((*x, *y), ' ')),
+            [x, y, 1] => Some(((*x, *y), '|')),
+            [x, y, 2] => Some(((*x, *y), '#')),
+            [x, y, 3] => {
+                paddle = Some((*x, *y));
+                Some(((*x, *y), '_'))
+            }
+            [x, y, 4] => {
+                ball = Some((*x, *y));
+                Some(((*x, *y), '*'))
+            }
+            _ => unreachable!(),
+        }));
+
+        if width == 0 {
+            computer.output().chunks(3).for_each(|chunk| match chunk {
+                [x, y, _] if *x >= 0 => {
+                    if *x > width {
+                        width = *x;
+                    }
+                    if *y > height {
+                        height = *y;
+                    }
+                }
+                _ => {}
+            })
+        }
+
+        // Show screen state
+        for y in 0..=height {
+            for x in 0..=width {
+                if let Some(tile) = screen.get(&(x, y)) {
+                    print!("{}", tile);
+                } else {
+                    print!(" ");
+                }
+            }
+            println!();
+        }
+        println!();
+
+        // Find out where the paddle and ball are, provide joystick input accordingly
+        if let (Some(ball), Some(paddle)) = (ball, paddle) {
+            let input = if paddle.0 < ball.0 {
+                1
+            } else if paddle.0 > ball.0 {
+                -1
+            } else {
+                0
+            };
+            computer.input(input);
+        } else {
+            panic!("ball or paddle missing");
+        }
+
+        computer.clear_output();
+
+        if res == ComputeResult::Halted {
+            break;
+        }
+    }
+
+    println!("Part 2: {}", score);
 }