Add solutions for day 2.

2016/day-02/input.txt

@@ -0,0 +1,5 @@
+RDRRDLRRUDRUUUULDDRDUULLDUULDURDDUDRULDLUDDRLRDUDDURRRRURDURLLRDRUUULDLLLURDRLLULLUULULLLDLLLRRURRLRDUULRURRUDRRDRLURLRURLLULRUURRUURDDLDRDLDLLUDUULLLUUUUDULLDRRUURLDURDDDDDRLLRRURDLUDRRUUDLRRLLRDURDUDDDLRDDRDLRULLUULRULRLLULDDRURUUDLDDULDRLLURDDUDDUDRDUDLDRRRDURRLDRDRLDLLDUDDDULULRRULRLLURDRRDDUUUUUULRUDLRRDURDLRDLUDLDURUDDUUURUDLUUULDLRDURDLDUUDLDDDURUUDUUDRLRDULLDUULUDRUDRLRRRDLLDRUDULRRUDDURLDRURRLLRRRDRLLDLULULRRUURRURLLUDRRLRULURLDDDDDURUDRRRRULLUUDLDDLUUL
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
+URLURDDRLLURRRLDLDLUDUURDRUDLLLRRDLUUULRRLURRRLUDUDLRLDDRUDLRRRULUDUDLLLULULLLRUDULDDDLLLRRRLRURDULUDDDULDLULURRRDLURDLRLLDUDRUDURDRRURULDRDUDLLRDDDUDDURLUULLULRDRRLDDLDURLRRRLDRDLDULRULRRRLRLLDULRDLURLRUUDURRUUDLLUDRUDLRLDUUDLURRRDDUUDUDRLDLDDRURDDLLDDRDLRLRDLLLUDLUUDRLRLRDDRDLRDLLUULLLLUULLDLLDLRDLRLRRLUUDLLRLRUDRURULRLRLULUDRLLUDDUDDULRLDDRUUUURULDRRULLLDUURULUDRLLURLRRLDLRRLDDRRRDUDDUDLDDLULUDDUURDLLLRLDLRDRUUUUUDDDLDRDDRRRLRURRRRDURDRURUDLURRURDRLRUUDDLDRRULLDURDRLRRDURURUULRDUDLDRDDLULULRDRRUDDRLLRLULRLLUUDRDUUDDUDLRUUDLLUULLRUULUDDLURRRLLDRLRRLLRULLDUULURLLLLUUULDR
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
+LURLUURLURDUUDRUDLDLLURRRDLDRRRULDDRRDRDUUDRUDURDDDURLUDDLULUULRRLLRULUDRDDRRRLDURDUDDURDDDLRLDDLULLDRDDLUUDUURRRLULRUURRRRLLULDUDRDUURRRURRDRDUDUDLUDULLDLDDRLUDRURDULURLURRLLURLLLRLUURLRUDLUDDRLURRUULULRLURRURUDURDLDLDDUDDRDLLRLLRRULDDRUDURUDDDUDLLRDLRUDULLLRRRUURUDUUULLRDUDRURUDULLDLLUUUDRULRLLRRDDDDUDULDRDRLLDDLLDDDURRUDURLDLRDRUURDDURLRDRURLRRLLRLULDRRLRUDURDUURRLUUULUDDDLRLULRDRLLURRRDLURDUUDRRRLUURRLLUDLUDLUULLRRDLLRDDRURRUURLDDLRLRLRUDLDLRLRDRRDLLLRDLRDUDLLDDDRD

2016/day-02/sample.txt

@@ -0,0 +1,4 @@
+ULL
+RRDDD
+LURDL
+UUUUD

2016/day-02/solution.rs

@@ -0,0 +1,85 @@
+use std::cmp::min;
+use std::io::prelude::*;
+use std::io::BufReader;
+use std::fs::File;
+use std::path::Path;
+use std::env;
+
+fn move_pos1(pos: i32, instruction: char) -> i32
+{
+    match instruction {
+        'U' => if pos > 3 { pos - 3 } else { pos },
+        'D' => if pos < 7 { pos + 3 } else { pos },
+        'L' => if pos % 3 != 1 { pos - 1 } else { pos },
+        'R' => if pos % 3 != 0 { pos + 1 } else { pos },
+        _   => panic!("Unsupported direction {}", instruction),
+    }
+}
+
+fn row_width(y: i32) -> i32
+{
+    min(2 * y + 1, 9 - 2 * y)
+}
+
+fn row_offset(y: i32) -> i32
+{
+    (5 - row_width(y)) / 2
+}
+
+fn is_legal(pos: (i32, i32)) -> bool {
+    let (x, y) = pos;
+    let width = row_width(y);
+    let offset = row_offset(y);
+
+    y >= 0 && y < 5 && x >= offset && x < offset + width
+}
+
+fn move_pos2(pos: (i32, i32), instruction: char) -> (i32, i32)
+{
+    let (x, y) = pos;
+    let new_pos = match instruction {
+        'U' => (x, y - 1),
+        'D' => (x, y + 1),
+        'L' => (x - 1, y),
+        'R' => (x + 1, y),
+        _   => panic!("Unsupported direction {}", instruction),
+    };
+
+    if is_legal(new_pos) { new_pos } else { pos }
+}
+
+fn pos2char(pos: (i32, i32)) -> String
+{
+    let (x, y) = pos;
+    let mut num = x + 1 - row_offset(y);
+    for i in 0..y {
+        num += row_width(i);
+    }
+
+    format!("{:X}", num)
+}
+
+fn main()
+{
+    let args: Vec<String> = env::args().collect();
+    let path = Path::new(&args[1]);
+    let f = File::open(&path).expect("Could not open file");
+    let reader = BufReader::new(f);
+
+    let mut pos1 = 5;
+    let mut pos2 = (0, 2);
+    let mut code1 = String::new();
+    let mut code2 = String::new();
+    for line in reader.lines() {
+        for instruction in line.unwrap().trim().chars() {
+            pos1 = move_pos1(pos1, instruction);
+            pos2 = move_pos2(pos2, instruction);
+        }
+
+        code1 += &pos1.to_string();
+        code2 += &pos2char(pos2);
+    }
+
+    println!("Code 1 is {}", code1);
+    println!("Code 2 is {}", code2);
+}