From 8d63b78e7031ea442404c0cb4ecf0e5c93972eeb Mon Sep 17 00:00:00 2001
From: Irene Knapp <ireneista@gmail.com>
Date: Fri, 24 Dec 2021 21:22:33 -0800
Subject: 25

---
 25/Cargo.toml      |  11 ++
 25/input           | 137 +++++++++++++++++++
 25/input-commented | 278 +++++++++++++++++++++++++++++++++++++++
 25/small           | 136 +++++++++++++++++++
 25/src/main.rs     | 118 +++++++++++++++++
 25/src/main.rs.bak | 379 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 25/tests/main.rs   |  17 +++
 Cargo.lock         |   8 ++
 Cargo.toml         |   1 +
 9 files changed, 1085 insertions(+)
 create mode 100644 25/Cargo.toml
 create mode 100644 25/input
 create mode 100644 25/input-commented
 create mode 100644 25/small
 create mode 100644 25/src/main.rs
 create mode 100644 25/src/main.rs.bak
 create mode 100644 25/tests/main.rs

diff --git a/25/Cargo.toml b/25/Cargo.toml
new file mode 100644
index 0000000..746f708
--- /dev/null
+++ b/25/Cargo.toml
@@ -0,0 +1,11 @@
+[package]
+name = "advent_25"
+version = "0.1.0"
+authors = ["Irene Knapp <ireneista@gmail.com>"]
+edition = "2018"
+
+[dependencies]
+advent_lib = { path = "../lib" }
+
+[dev-dependencies]
+assert_cmd = "0.10"
diff --git a/25/input b/25/input
new file mode 100644
index 0000000..051ac54
--- /dev/null
+++ b/25/input
@@ -0,0 +1,137 @@
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+.>.>..>>.....v.>v...vv.v>.>>v>>.>>>.......>v>>>.>v.>.>.v.v.>.v.>>...vvvv>vv.v..v..>.>v..v....v>v>>>v..vv...v>v.>.v..>.>..>>>>v>.v...v..v..v
+>>.v..>v>>...>.>..v>..>.>vvv.>v..v.v>.v...v>..>>.vv.v>>v.v>.>v>v>....v...>>.>v.v..v>v>.>.>.>.>v.>.vv.vv..>....>.v.....>......vv..>.v>.v....
+>>.v.>>>vv>>...v..v.>>v.v..vvv.>vv...v>...v>.>>..v.>.v..v.v...>.vvv.>>>vvv>.vv.v.....v>v.>>.v..>.vv>.v>v..v>vv..vv.v.>..>>.>...>>...v..v>v>
+>....v>>>>vv>.>>.....>.v...>.>..v>v..v.>>vvv>>....>vv>v>v>....>vv..v.>.>..v.v>>..v.>.v>>..vv..v>.>.>....v>..>>vvv.>..v>.v>.v.>v>.>..v..>...
+.>vv>>vv>..>v...v>.>v>>v.vv>.v....v..vv.>.>.>..>...v..>v..v..>v...v.>>vv..v>>v.>vv>v.>>....v...>.>.>..v...v...>..v.vv....v.vv.....>..>>..v.
+.>....>.>.v>..v..>>...>>.>.>>..>v.>..>>v>vv...vvv..vv.>v.>..v>>.....v.v...v.v...>>vv.vvv...>>.vv>>>.v.>....v>vv..>v>>.>.>.v>.v>.>>.>..>v>.v
+>>>.vv>vv..>v........v..>vv>>.>>v>.v.>...>.vv..vvv.v..>..v>vvv>v....>....vv>..v..v>v...>>v..>.v>.>v>>.......v.>v.........>.v>.v.>.>..>..vv>
+..>..>.>.....v.vv.>vvv..>v...>v.>....>.>..v.>.....>>..>v..v...>v.v.v....>v..>........v...>>>>..>..vv>..v.>>v.>.>v....vv>>vv......v..v..v>vv
+.v>v.vv>v>>>..v>v.>..>.vvvvvv.>>.v..>>.v..>vvv>...>.>.>..>.v>vv...v.v>v..v.>.v>>>v..>v>.v..>v...v.vv.v..vvv.>v....>.vv...>..vv.>.>.>v.>..v.
+>>..vv..>>vv>vvv.v..>>>>.v>vv>>.v.>..v>>.v.>..v>>v>..>.>v.>v>..>>v.>>...>>.>.v.....v.>v.....v>..>vv...v..vvvvv.vv.>v>..>v...>.v>>v....>>>v.
+.>.vv...v>.v>>v>.......v.v.v..v..v....>>>.>..v.......>v.>.>..vv...v>v.v.>.>.v>vv>>vv..>.>.v...v..>..>.vv.>vvv.>>v.>vv>...>.....v>v.v.v>..>.
+.>..>>.v...vvvv>v....v...v.v.v...vv...>.v>..v.v>v..>>.vvvv>vv...v>v>......>>.>.v..v>>.>v.vv..vvv>>.>...>>.v..>v.>v...>v...v.v>vv.vv>>...v>>
+.v...>..vv..>v..vv>.v..vv.>.v>v>>v..>>.v.>v.>v>>vv>..v.v.v>...>..v.>.v...>v.....vv...>v>vvv>v......>..v....>vv....v.>>...v...>..>>.vv.v.vvv
+>..>...v.>v>v>v>vvvv.>>vv>v.v..>>v.v..v...>v.v>>v..>....>v.v.>.>...>vv..>>.....v>.vv.>.>v.>v.....v>v...vvv>>..>>.>..v.v>>v.>.>.v....>..v.>.
+....>.v>>>.......>.vv>..v...v..v.....v.>v>....v>v.>>vv...v>v.>.vv>>.v>>v........v>...vv>.>..v......>vv>>>v>>v>.>v..>...v...vv...>.>.v>v>v..
+v>>>v....>>.v>>.>..>.>v>.>..>.v..v.>.>>.vv>>.>....>.v.v..>vvv.>v.>...v..>v....>>v>...vv..v>vv>.....>.v.v.>>>>>>>>...>v.v.>>..>..v.v>v>>.>.>
+....v>v..>.v>>.....v>>..v.>.>....>...>..>.v>..v>...>..>...>.v.vvv.>>v..>......v>>>>v>..vv>>.>>>.v>>.>.v>.>v>>>.>..v.>.v.v>.>..v>.>..>.>>vv>
+>v..>.vv.>.v...>.v.....vv..v..>.v..>>.>v..>..>>.vvvv>v>.v....>.v.>v.......v.....v.>>..>vv...v>>.vv>..>vvvv>....v...v..>>v.>v>.vvv..v>v>..vv
+>>.......v>.vv>.vv>>..v..>...vvv...vv.>...vvvvv.>....>..>>.vv.v>...v..v..v...v>.>...>v>.>v>>..>vvv.vv.>.v.v....>v.>>>....>.....v...v....v.>
+>..v.vvv.vv>>v>>.>......v..>vv>....>v>>...v>.>.vv>>.>..>...>v>...vv>v>.>>vv....>..>.v.v>.v..vv>v.....>v>vvv.v>.>.>.v......>......>.>>.>>>>.
+>>vv....>v...>.v.>..v.vv..vv....>>>v......v..v.v....v.vvv>>.>.v>.v>.v>..v.v.>...v>v.>v>>.vvv..>.>.>..v>>.>.v...>vv.v>.v..vv>v.v>.v.>...>..>
+>...>v..v..>...>.>v..vv.>v.>v>v....v>v...v....>.>..>..v>.v.v>.v..v..v.>...vv.>...vv>.>vv...v>v..>>>v...>...>>>.vv>..>v.>v.v....v>.>..v>>..v
+.vv..>v>>v...v.....>...v...vv.>.>vv>vv.>>...v.......v>.v..v>>...>vv.>..v.v.v>v>>.>v>..>..v.v...v.>v>.v..>>.>v....v.>.>v.v...>.vv>..>>.>>v..
diff --git a/25/input-commented b/25/input-commented
new file mode 100644
index 0000000..1ea20b8
--- /dev/null
+++ b/25/input-commented
@@ -0,0 +1,278 @@
+; 0 0 0 0
+inp w        ; w = digit[0]
+mul x 0      ; nop
+add x z      ; nop
+mod x 26     ; nop
+div z 1      ; nop                  **NOTE** parameter M[0] = 1
+add x 10     ; x = 10               **NOTE** parameter N[0] = 10
+eql x w      ; x = (digit[0] == 10), which is 0 for valid input
+eql x 0      ; x = (digit[0] != 10), which is 1 for valid input
+mul y 0      ; nop
+add y 25     ; y = 25
+mul y x      ; y = 25 if valid digit, 0 otherwise
+add y 1      ; y = 26 if valid digit, 1 otherwise
+mul z y      ; nop
+mul y 0      ; y = 0
+add y w      ; y = digit[0]
+add y 10     ; y = digit[0] + 10    **NOTE** parameter O[0] = 10
+mul y x      ; y = digit[0] + 10 if valid digit, 0 otherwise
+add z y      ; z = digit[0] + 10 if valid digit, 0 otherwise
+
+let m = vec![1, 1, 1, 26, 1, 26, 1, 26, 1, 1, 26, 26, 26, 26];
+let n = vec![10, 13, 15, -12, 14, -2, 13, -12, 15, 11, -3, -13, -12, -13];
+let o = vec![10, 5, 12, 12, 6, 4, 15, 3, 7, 11, 2, 12, 4, 11];
+for i in 0 .. 14 {
+  w = input.pop();
+  x = if ((z % 26) / m[i] + n[i]) != w { 1 } else { 0 };
+  z = z * (25 * x + 1) + (w + o[i]) * x;
+}
+
+; _ _ a a    where a = digit[0] + 10 if valid digit, 0 otherwise
+inp w        ; w = digit[1]
+mul x 0      ; x = 0
+add x z      ; x = a
+mod x 26     ; x = a % 26
+div z 1      ; nop                  **NOTE** parameter M[0] = 1
+add x 13     ; x = a % 26 + 13      **NOTE** parameter N[1] = 13
+eql x w      ; x = (a % 26 + 13) == digit[1]
+eql x 0      ; x = (a % 26 + 13) != digit[1], 1 for valid-so-far
+mul y 0      ; y = 0
+add y 25     ; y = 25
+mul y x      ; y = 25 if valid-so-far, 0 otherwise
+add y 1      ; y = 26 if valid-so-far, 1 otherwise
+mul z y      ; z = a * 26 if valid-so-far, a otherwise
+mul y 0      ; y = 0
+add y w      ; y = digit[1]
+add y 5      ; y = digit[1] + 5     **NOTE** parameter O[1] = 5
+mul y x      ; y = digit[1] + 5 if valid digit, 0 otherwise
+add z y      ; z += y, thus fail if y is nonzero
+; fail if z is nonzero
+
+inp w
+mul x 0
+add x z
+mod x 26
+div z 1      ; note
+add x 15     ; note
+eql x w
+eql x 0
+mul y 0
+add y 25
+mul y x
+add y 1
+mul z y
+mul y 0
+add y w
+add y 12     ; note
+mul y x
+add z y
+
+inp w
+mul x 0
+add x z
+mod x 26
+div z 26     ; note
+add x -12    ; note
+eql x w
+eql x 0
+mul y 0
+add y 25
+mul y x
+add y 1
+mul z y
+mul y 0
+add y w
+add y 12     ; note
+mul y x
+add z y
+
+inp w
+mul x 0
+add x z
+mod x 26
+div z 1      ; note
+add x 14     ; note
+eql x w
+eql x 0
+mul y 0
+add y 25
+mul y x
+add y 1
+mul z y
+mul y 0
+add y w
+add y 6      ; note
+mul y x
+add z y
+
+inp w
+mul x 0
+add x z
+mod x 26
+div z 26    ; note
+add x -2    ; note
+eql x w
+eql x 0
+mul y 0
+add y 25
+mul y x
+add y 1
+mul z y
+mul y 0
+add y w
+add y 4     ; note
+mul y x
+add z y
+
+inp w
+mul x 0
+add x z
+mod x 26
+div z 1     ; note
+add x 13    ; note
+eql x w
+eql x 0
+mul y 0
+add y 25
+mul y x
+add y 1
+mul z y
+mul y 0
+add y w
+add y 15    ; note
+mul y x
+add z y
+
+inp w
+mul x 0
+add x z
+mod x 26
+div z 26    ; note
+add x -12   ; note
+eql x w
+eql x 0
+mul y 0
+add y 25
+mul y x
+add y 1
+mul z y
+mul y 0
+add y w
+add y 3     ; note
+mul y x
+add z y
+
+inp w
+mul x 0
+add x z
+mod x 26
+div z 1     ; note
+add x 15    ; note
+eql x w
+eql x 0
+mul y 0
+add y 25
+mul y x
+add y 1
+mul z y
+mul y 0
+add y w
+add y 7     ; note
+mul y x
+add z y
+
+inp w
+mul x 0
+add x z
+mod x 26
+div z 1     ; note
+add x 11    ; note
+eql x w
+eql x 0
+mul y 0
+add y 25
+mul y x
+add y 1
+mul z y
+mul y 0
+add y w
+add y 11    ; note
+mul y x
+add z y
+
+inp w
+mul x 0
+add x z
+mod x 26
+div z 26    ; note
+add x -3    ; note
+eql x w
+eql x 0
+mul y 0
+add y 25
+mul y x
+add y 1
+mul z y
+mul y 0
+add y w
+add y 2     ; note
+mul y x
+add z y
+
+inp w
+mul x 0
+add x z
+mod x 26
+div z 26    ; note
+add x -13   ; note
+eql x w
+eql x 0
+mul y 0
+add y 25
+mul y x
+add y 1
+mul z y
+mul y 0
+add y w
+add y 12    ; note
+mul y x
+add z y
+
+inp w
+mul x 0
+add x z
+mod x 26
+div z 26    ; note
+add x -12   ; note
+eql x w
+eql x 0
+mul y 0
+add y 25
+mul y x
+add y 1
+mul z y
+mul y 0
+add y w
+add y 4     ; note
+mul y x
+add z y
+
+inp w
+mul x 0
+add x z
+mod x 26
+div z 26    ; note
+add x -13   ; note
+eql x w
+eql x 0
+mul y 0
+add y 25
+mul y x
+add y 1
+mul z y
+mul y 0
+add y w
+add y 11    ; note
+mul y x
+add z y
+
diff --git a/25/small b/25/small
new file mode 100644
index 0000000..4e496e9
--- /dev/null
+++ b/25/small
@@ -0,0 +1,136 @@
+--- scanner 0 ---
+404,-588,-901
+528,-643,409
+-838,591,734
+390,-675,-793
+-537,-823,-458
+-485,-357,347
+-345,-311,381
+-661,-816,-575
+-876,649,763
+-618,-824,-621
+553,345,-567
+474,580,667
+-447,-329,318
+-584,868,-557
+544,-627,-890
+564,392,-477
+455,729,728
+-892,524,684
+-689,845,-530
+423,-701,434
+7,-33,-71
+630,319,-379
+443,580,662
+-789,900,-551
+459,-707,401
+
+--- scanner 1 ---
+686,422,578
+605,423,415
+515,917,-361
+-336,658,858
+95,138,22
+-476,619,847
+-340,-569,-846
+567,-361,727
+-460,603,-452
+669,-402,600
+729,430,532
+-500,-761,534
+-322,571,750
+-466,-666,-811
+-429,-592,574
+-355,545,-477
+703,-491,-529
+-328,-685,520
+413,935,-424
+-391,539,-444
+586,-435,557
+-364,-763,-893
+807,-499,-711
+755,-354,-619
+553,889,-390
+
+--- scanner 2 ---
+649,640,665
+682,-795,504
+-784,533,-524
+-644,584,-595
+-588,-843,648
+-30,6,44
+-674,560,763
+500,723,-460
+609,671,-379
+-555,-800,653
+-675,-892,-343
+697,-426,-610
+578,704,681
+493,664,-388
+-671,-858,530
+-667,343,800
+571,-461,-707
+-138,-166,112
+-889,563,-600
+646,-828,498
+640,759,510
+-630,509,768
+-681,-892,-333
+673,-379,-804
+-742,-814,-386
+577,-820,562
+
+--- scanner 3 ---
+-589,542,597
+605,-692,669
+-500,565,-823
+-660,373,557
+-458,-679,-417
+-488,449,543
+-626,468,-788
+338,-750,-386
+528,-832,-391
+562,-778,733
+-938,-730,414
+543,643,-506
+-524,371,-870
+407,773,750
+-104,29,83
+378,-903,-323
+-778,-728,485
+426,699,580
+-438,-605,-362
+-469,-447,-387
+509,732,623
+647,635,-688
+-868,-804,481
+614,-800,639
+595,780,-596
+
+--- scanner 4 ---
+727,592,562
+-293,-554,779
+441,611,-461
+-714,465,-776
+-743,427,-804
+-660,-479,-426
+832,-632,460
+927,-485,-438
+408,393,-506
+466,436,-512
+110,16,151
+-258,-428,682
+-393,719,612
+-211,-452,876
+808,-476,-593
+-575,615,604
+-485,667,467
+-680,325,-822
+-627,-443,-432
+872,-547,-609
+833,512,582
+807,604,487
+839,-516,451
+891,-625,532
+-652,-548,-490
+30,-46,-14
diff --git a/25/src/main.rs b/25/src/main.rs
new file mode 100644
index 0000000..2e137c7
--- /dev/null
+++ b/25/src/main.rs
@@ -0,0 +1,118 @@
+use advent_lib::prelude::*;
+
+#[derive(Debug,Clone,Eq,PartialEq)]
+enum Cell {
+  Empty,
+  East,
+  South,
+}
+
+
+fn main() -> Result<()> {
+  let mut args = std::env::args();
+  if args.len() != 2 {
+    eprintln!("Usage: advent input");
+  }
+  let _ = args.next();
+  let filename = args.next().unwrap();
+
+  let input = advent_lib::read_lines_file(&filename)?;
+
+  let mut initial_grid = Vec::new();
+  for line in &input {
+    let mut row = Vec::new();
+    for c in line.chars() {
+      row.push(match c {
+        '.' => Cell::Empty,
+        '>' => Cell::East,
+        'v' => Cell::South,
+        _ => panic!("Unrecognized character."),
+      });
+    }
+    initial_grid.push(row);
+  }
+
+  let mut i = 0;
+  let mut grid = initial_grid.clone();
+  loop {
+    i += 1;
+    let (anything_moved, new_grid) = iterate(&grid);
+    grid = new_grid;
+
+    println!("iteration {}", i);
+    debug_grid(&grid);
+
+    if !anything_moved {
+      break;
+    }
+  }
+  println!("{}", i);
+
+  Ok(())
+}
+
+
+fn iterate(grid: &Vec<Vec<Cell>>) -> (bool, Vec<Vec<Cell>>) {
+  let mut anything_moved = false;
+
+  let height = grid.len();
+  let width = grid[0].len();
+
+  let mut new_grid = Vec::new();
+  for _ in 0 .. height {
+    let mut row = Vec::new();
+    for _ in 0 .. width {
+      row.push(Cell::Empty);
+    }
+    new_grid.push(row);
+  }
+
+  for y in 0 .. height {
+    for x in 0 .. width {
+      if grid[y][x] == Cell::East {
+        let new_x = (x + 1) % width;
+        if grid[y][new_x] == Cell::Empty {
+          new_grid[y][new_x] = Cell::East;
+          anything_moved = true;
+        } else {
+          new_grid[y][x] = Cell::East;
+        }
+      }
+    }
+  }
+
+  for y in 0 .. height {
+    for x in 0 .. width {
+      if grid[y][x] == Cell::South {
+        let new_y = (y + 1) % height;
+        if new_grid[new_y][x] == Cell::Empty
+          && grid[new_y][x] != Cell::South
+        {
+          new_grid[new_y][x] = Cell::South;
+          anything_moved = true;
+        } else {
+          new_grid[y][x] = Cell::South;
+        }
+      }
+    }
+  }
+
+  (anything_moved, new_grid)
+}
+
+
+#[allow(dead_code)]
+fn debug_grid(grid: &Vec<Vec<Cell>>) {
+  for row in grid {
+    for cell in row {
+      match cell {
+        Cell::Empty => print!("."),
+        Cell::East => print!(">"),
+        Cell::South => print!("v"),
+      }
+    }
+    println!("");
+  }
+  println!("");
+}
+
diff --git a/25/src/main.rs.bak b/25/src/main.rs.bak
new file mode 100644
index 0000000..37bfd78
--- /dev/null
+++ b/25/src/main.rs.bak
@@ -0,0 +1,379 @@
+use advent_lib::prelude::*;
+
+#[derive(Debug,Clone,Eq,PartialEq)]
+enum Instruction {
+  Inp(Variable),
+  Add(Variable, Expression),
+  Mul(Variable, Expression),
+  Div(Variable, Expression),
+  Mod(Variable, Expression),
+  Eql(Variable, Expression),
+}
+
+#[derive(Debug,Clone,Eq,PartialEq)]
+enum Expression {
+  Variable(Variable),
+  Literal(i64),
+}
+
+#[derive(Debug,Clone,Copy,Eq,PartialEq)]
+enum Variable {
+  W,
+  X,
+  Y,
+  Z,
+}
+
+#[derive(Debug,Clone,Eq,PartialEq)]
+struct State {
+  w: i64,
+  x: i64,
+  y: i64,
+  z: i64,
+  program_counter: usize,
+  input: Vec<i64>,
+}
+
+
+fn main() -> Result<()> {
+  let mut args = std::env::args();
+  if args.len() != 2 {
+    eprintln!("Usage: advent input");
+  }
+  let _ = args.next();
+  let filename = args.next().unwrap();
+
+  let input = advent_lib::read_lines_file(&filename)?;
+
+  let mut program = Vec::new();
+  for line in &input {
+    let words: Vec<&str> = line.split_whitespace().collect();
+    match words[0] {
+      "inp" => {
+        let a = parse_variable(words[1]);
+        program.push(Instruction::Inp(a));
+      },
+      "add" => {
+        let a = parse_variable(words[1]);
+        let b = parse_expression(words[2]);
+        program.push(Instruction::Add(a, b));
+      },
+      "mul" => {
+        let a = parse_variable(words[1]);
+        let b = parse_expression(words[2]);
+        program.push(Instruction::Mul(a, b));
+      },
+      "div" => {
+        let a = parse_variable(words[1]);
+        let b = parse_expression(words[2]);
+        program.push(Instruction::Div(a, b));
+      },
+      "mod" => {
+        let a = parse_variable(words[1]);
+        let b = parse_expression(words[2]);
+        program.push(Instruction::Mod(a, b));
+      },
+      "eql" => {
+        let a = parse_variable(words[1]);
+        let b = parse_expression(words[2]);
+        program.push(Instruction::Eql(a, b));
+      },
+      _ => panic!("not an instruction"),
+    }
+  }
+
+  let initial_state = State {
+    w: 0,
+    x: 0,
+    y: 0,
+    z: 0,
+    input: Vec::new(),
+    program_counter: 0,
+  };
+
+  /*
+  for w in 1 .. 10 {
+    for z in 254176 .. 394784 {
+    //for z in 9776 .. 15185 {
+      let mut ws = vec![w];
+
+      let mut state = initial_state.clone();
+      state.input = ws.clone();
+      state.z = z;
+      //state.program_counter = 0; // start of iteration 0
+      //state.program_counter = 18; // start of iteration 1
+      //state.program_counter = 36; // start of iteration 2
+      //state.program_counter = 54; // start of iteration 3
+      //state.program_counter = 72; // start of iteration 4
+      //state.program_counter = 90; // start of iteration 5
+      //state.program_counter = 108; // start of iteration 6
+      //state.program_counter = 126; // start of iteration 7
+      //state.program_counter = 144; // start of iteration 8
+      //state.program_counter = 162; // start of iteration 9
+      state.program_counter = 180; // start of iteration 10
+
+      run_until(&mut state, &program, 198); // start of iteration 11
+      if state.x == 0
+      //if state.z >= 9776 && state.z <= 15184
+        //&& state.z / 26 - 3 >= 1 && state.z / 26 - 3 <= 9
+      {
+        println!("yay {} {}", state.z / 26, state.x);
+        let new_w = state.z / 26 - 3;
+        ws.push(new_w);
+        state.input.push(new_w);
+      } else {
+        continue;
+      }
+
+      run_until(&mut state, &program, 216); // start of iteration 12
+      if state.z >= 376 && state.z <= 584
+        && (state.z - 350) / 26 >= 1 && (state.z - 350) / 26 <= 9
+      {
+        let new_w = state.z / 26 - 12;
+        ws.push(new_w);
+        state.input.push(new_w);
+      } else {
+        continue;
+      }
+
+      run_until(&mut state, &program, 234); // start of iteration 13
+      if state.z >= 14 && state.z <= 22 {
+        let new_w = state.z - 13;
+        ws.push(new_w);
+        state.input.push(new_w);
+      } else {
+        continue;
+      }
+
+      run(&mut state, &program);
+      if state.z == 0 {
+        println!("success! w = {:?}, z = {}", ws, z);
+      }
+    }
+  }
+  */
+
+  /*
+  let mut input = Vec::new();
+  for _ in 0 .. 14 {
+    input.push(9);
+  }
+  input[13] = 9;
+
+  let mut odometer = 0;
+  loop {
+    if input[0] == 3 {
+      let mut state = initial_state.clone();
+      //state.input = input.clone();
+
+      run(&mut state, &program);
+      //run_fake(&mut state);
+      if state.z == 0 {
+        break;
+      }
+
+      odometer += 1;
+      if odometer % 1 == 0 {
+        print!("iteration {} ", odometer);
+        debug_input(&input);
+        debug_state(&state);
+      }
+    }
+
+    for i in 0 .. 14 {
+      input[i] -= 1;
+      if input[i] == 0 {
+        input[i] = 9;
+        if i == 13 {
+          println!("tried everything");
+          break;
+        }
+      } else {
+        break;
+      }
+    }
+  }
+  debug_input(&input);
+  */
+
+
+  let mut state = initial_state.clone();
+  for w in 1 .. 10 {
+  run_until(&mut state, &program, 18); // start of iteration 1
+  run_until(&mut state, &program, 36); // start of iteration 2
+  run_until(&mut state, &program, 54); // start of iteration 3
+  run_until(&mut state, &program, 72); // start of iteration 4
+  run_until(&mut state, &program, 90); // start of iteration 5
+  run_until(&mut state, &program, 108); // start of iteration 6
+  run_until(&mut state, &program, 126); // start of iteration 7
+  run_until(&mut state, &program, 144); // start of iteration 8
+  run_until(&mut state, &program, 162); // start of iteration 9
+  run_until(&mut state, &program, 180); // start of iteration 10
+  run_until(&mut state, &program, 198); // start of iteration 11
+  run_until(&mut state, &program, 216); // start of iteration 12
+  run_until(&mut state, &program, 234); // start of iteration 13
+
+
+  Ok(())
+}
+
+
+fn parse_expression(word: &str) -> Expression {
+  match word {
+    "w" => Expression::Variable(Variable::W),
+    "x" => Expression::Variable(Variable::X),
+    "y" => Expression::Variable(Variable::Y),
+    "z" => Expression::Variable(Variable::Z),
+    _ => Expression::Literal(word.parse::<i64>().unwrap()),
+  }
+}
+
+
+fn parse_variable(word: &str) -> Variable {
+  match word {
+    "w" => Variable::W,
+    "x" => Variable::X,
+    "y" => Variable::Y,
+    "z" => Variable::Z,
+    _ => panic!("not a variable name"),
+  }
+}
+
+
+#[allow(dead_code)]
+fn run(state: &mut State, program: &Vec<Instruction>) {
+  loop {
+    if is_done(state, program) {
+      break;
+    }
+    iterate(state, program);
+  }
+}
+
+
+#[allow(dead_code)]
+fn run_until(state: &mut State, program: &Vec<Instruction>, end: usize) {
+  loop {
+    if state.program_counter == end {
+      break;
+    }
+    iterate(state, program);
+  }
+}
+
+
+fn iterate(state: &mut State, program: &Vec<Instruction>) {
+  match &program[state.program_counter] {
+    Instruction::Inp(a) => {
+      //debug_state(state);
+
+      let result = state.input.pop().unwrap();
+      set_variable(state, &a, result);
+    },
+    Instruction::Add(a, b) => {
+      let a_value = evaluate_variable(state, &a);
+      let b_value = evaluate_expression(state, &b);
+      let result = a_value + b_value;
+      set_variable(state, &a, result);
+    },
+    Instruction::Mul(a, b) => {
+      let a_value = evaluate_variable(state, &a);
+      let b_value = evaluate_expression(state, &b);
+      let result = a_value * b_value;
+      set_variable(state, &a, result);
+    },
+    Instruction::Div(a, b) => {
+      let a_value = evaluate_variable(state, &a);
+      let b_value = evaluate_expression(state, &b);
+      let result = a_value / b_value;
+      set_variable(state, &a, result);
+    },
+    Instruction::Mod(a, b) => {
+      let a_value = evaluate_variable(state, &a);
+      let b_value = evaluate_expression(state, &b);
+      let result = a_value % b_value;
+      set_variable(state, &a, result);
+    },
+    Instruction::Eql(a, b) => {
+      let a_value = evaluate_variable(state, &a);
+      let b_value = evaluate_expression(state, &b);
+      let result = if a_value == b_value { 1 } else { 0 };
+      set_variable(state, &a, result);
+    },
+  }
+
+  state.program_counter += 1;
+}
+
+
+fn evaluate_expression(state: &State, expression: &Expression) -> i64 {
+  match expression {
+    Expression::Variable(Variable::W) => state.w,
+    Expression::Variable(Variable::X) => state.x,
+    Expression::Variable(Variable::Y) => state.y,
+    Expression::Variable(Variable::Z) => state.z,
+    Expression::Literal(n) => *n,
+  }
+}
+
+
+fn evaluate_variable(state: &State, variable: &Variable) -> i64 {
+  match variable {
+    Variable::W => state.w,
+    Variable::X => state.x,
+    Variable::Y => state.y,
+    Variable::Z => state.z,
+  }
+}
+
+
+fn set_variable(state: &mut State, variable: &Variable, value: i64) {
+  match variable {
+    Variable::W => { state.w = value; },
+    Variable::X => { state.x = value; },
+    Variable::Y => { state.y = value; },
+    Variable::Z => { state.z = value; },
+  }
+}
+
+
+fn is_done(state: &State, program: &Vec<Instruction>) -> bool {
+  if state.program_counter >= program.len() {
+    return true;
+  }
+
+  false
+}
+
+
+#[allow(dead_code)]
+fn debug_input(input: &Vec<i64>) {
+  for digit in input.iter().rev() {
+    print!("{}", digit);
+  }
+  println!("");
+}
+
+
+#[allow(dead_code)]
+fn debug_state(state: &State) {
+  println!("line {}:   {}    {}    {}    {}", state.program_counter, state.w,
+    state.x, state.y, state.z);
+}
+
+
+#[allow(dead_code)]
+fn run_fake(state: &mut State) {
+  //           0    1   2    3   4   5   6    7   8   9  10   11   12   13
+  let m = vec![1,   1,  1,  26,  1, 26,  1,  26,  1,  1, 26,  26,  26,  26];
+  let n = vec![10, 13, 15, -12, 14, -2, 13, -12, 15, 11, -3, -13, -12, -13];
+  let o = vec![10,  5, 12,  12,  6,  4, 15,   3,  7, 11,  2,  12,   4,  11];
+  for i in 0 .. 14 {
+    state.w = state.input.pop().unwrap();
+    state.x = state.z % 26;
+    state.z /= m[i];
+    state.x = if state.x + n[i] != state.w { 1 } else { 0 };
+    state.z = state.z * (25 * state.x + 1) + (state.w + o[i]) * state.x;
+  }
+}
+
diff --git a/25/tests/main.rs b/25/tests/main.rs
new file mode 100644
index 0000000..6f37464
--- /dev/null
+++ b/25/tests/main.rs
@@ -0,0 +1,17 @@
+use assert_cmd::prelude::*;
+//use predicates::prelude::*;
+use std::process::Command;
+
+
+#[test]
+fn personal_input() -> Result<(), Box<dyn std::error::Error>> {
+  let mut command = Command::cargo_bin("advent_23")?;
+
+  command.arg("input");
+  command.assert().success().stdout(
+      "13336\n\
+      53308\n");
+
+  Ok(())
+}
+
diff --git a/Cargo.lock b/Cargo.lock
index 48ca432..37d3278 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -194,6 +194,14 @@ dependencies = [
  "assert_cmd",
 ]
 
+[[package]]
+name = "advent_25"
+version = "0.1.0"
+dependencies = [
+ "advent_lib",
+ "assert_cmd",
+]
+
 [[package]]
 name = "advent_lib"
 version = "0.1.0"
diff --git a/Cargo.toml b/Cargo.toml
index 679f317..382370d 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -25,4 +25,5 @@ members = [
   "22",
   "23",
   "24",
+  "25",
 ]
-- 
cgit 1.4.1