Solutions for 2022, as well as 2015-2018 and 2019 up to day 11

2017/day01-inverse_captcha/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "day01-inverse_captcha"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

2017/day01-inverse_captcha/challenge.txt

@@ -0,0 +1,50 @@
+\--- Day 1: Inverse Captcha ---
+----------
+
+The night before Christmas, one of Santa's Elves calls you in a panic. "The printer's broken! We can't print the *Naughty or Nice List*!" By the time you make it to sub-basement 17, there are only a few minutes until midnight. "We have a big problem," she says; "there must be almost *fifty* bugs in this system, but nothing else can print The List. Stand in this square, quick! There's no time to explain; if you can convince them to pay you in *stars*, you'll be able to--" She pulls a lever and the world goes blurry.
+
+When your eyes can focus again, everything seems a lot more pixelated than before. She must have sent you inside the computer! You check the system clock: *25 milliseconds* until midnight. With that much time, you should be able to collect all *fifty stars* by December 25th.
+
+Collect stars by solving puzzles. Two puzzles will be made available on each ~~day~~ millisecond in the Advent calendar; the second puzzle is unlocked when you complete the first. Each puzzle grants *one star*. Good luck!
+
+You're standing in a room with "digitization quarantine" written in LEDs along one wall. The only door is locked, but it includes a small interface. "Restricted Area - Strictly No Digitized Users Allowed."
+
+It goes on to explain that you may only leave by solving a [captcha](https://en.wikipedia.org/wiki/CAPTCHA) to prove you're *not* a human. Apparently, you only get one millisecond to solve the captcha: too fast for a normal human, but it feels like hours to you.
+
+The captcha requires you to review a sequence of digits (your puzzle input) and find the *sum* of all digits that match the *next* digit in the list. The list is circular, so the digit after the last digit is the *first* digit in the list.
+
+For example:
+
+* `1122` produces a sum of `3` (`1` + `2`) because the first digit (`1`) matches the second digit and the third digit (`2`) matches the fourth digit.
+* `1111` produces `4` because each digit (all `1`) matches the next.
+* `1234` produces `0` because no digit matches the next.
+* `91212129` produces `9` because the only digit that matches the next one is the last digit, `9`.
+
+*What is the solution* to your captcha?
+
+Your puzzle answer was `1182`.
+
+\--- Part Two ---
+----------
+
+You notice a progress bar that jumps to 50% completion. Apparently, the door isn't yet satisfied, but it did emit a *star* as encouragement. The instructions change:
+
+Now, instead of considering the *next* digit, it wants you to consider the digit *halfway around* the circular list. That is, if your list contains `10` items, only include a digit in your sum if the digit `10/2 = 5` steps forward matches it. Fortunately, your list has an even number of elements.
+
+For example:
+
+* `1212` produces `6`: the list contains `4` items, and all four digits match the digit `2` items ahead.
+* `1221` produces `0`, because every comparison is between a `1` and a `2`.
+* `123425` produces `4`, because both `2`s match each other, but no other digit has a match.
+* `123123` produces `12`.
+* `12131415` produces `4`.
+
+*What is the solution* to your new captcha?
+
+Your puzzle answer was `1152`.
+
+Both parts of this puzzle are complete! They provide two gold stars: \*\*
+
+At this point, all that is left is for you to [admire your Advent calendar](/2017).
+
+If you still want to see it, you can [get your puzzle input](1/input).

2017/day01-inverse_captcha/src/lib.rs

@@ -0,0 +1,63 @@
+pub fn run(input: &str) -> (usize, usize) {
+    let in_bytes = input.as_bytes();
+    let first = in_bytes.windows(2)
+        .filter(|b| b[0] == b[1])
+        .map(|b| (b[0] - b'0') as usize)
+        .sum::<usize>() + 
+            if in_bytes.first().unwrap() == in_bytes.last().unwrap() { 
+                (*in_bytes.first().unwrap() - b'0') as usize 
+            } else { 
+                0 
+            };
+    let half = in_bytes.len()/2;
+    let second = (0..half)
+        .filter(|i| in_bytes[*i] == in_bytes[*i+half])
+        .map(|i| (in_bytes[i] - b'0') as usize)
+        .sum::<usize>() * 2;
+    (first, second)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use std::fs::read_to_string;
+
+    fn read_file(name: &str) -> String {
+        read_to_string(name).expect(&format!("Unable to read file: {name}")[..]).trim().to_string()
+    }
+
+    #[test]
+    fn test_sample() {
+        let sample_inputs = [
+            "1122",
+            "1111",
+            "1234",
+            "91212129",
+            "1212",
+            "1221",
+            "123425",
+            "123123",
+            "12131415",
+        ];
+        let expected = [
+            (3,0),
+            (4,4),
+            (0,0),
+            (9,6),
+            (0,6),
+            (3,0),
+            (0,4),
+            (0,12),
+            (0,4),
+        ];
+        for (idx, sample_input) in sample_inputs.iter().enumerate() {
+            assert_eq!(run(sample_input), expected[idx]);
+        }
+    }
+
+    #[test]
+    fn test_challenge() {
+        let challenge_input = read_file("tests/challenge_input");
+        assert_eq!(run(&challenge_input), (1182, 1152));
+    }
+}

2017/day01-inverse_captcha/tests/challenge_input

@@ -0,0 +1 @@
+61697637962276641366442297247367117738114719863473648131982449728688116728695866572989524473392982963976411147683588415878214189996163533584547175794158118148724298832798898333399786561459152644144669959887341481968319172987357989785791366732849932788343772112176614723858474959919713855398876956427631354172668133549845585632211935573662181331613137869866693259374322169811683635325321597242889358147123358117774914653787371368574784376721652181792371635288376729784967526824915192526744935187989571347746222113625577963476141923187534658445615596987614385911513939292257263723518774888174635963254624769684533531443745729344341973746469326838186248448483587477563285867499956446218775232374383433921835993136463383628861115573142854358943291148766299653633195582135934544964657663198387794442443531964615169655243652696782443394639169687847463721585527947839992182415393199964893658322757634675274422993237955354185194868638454891442893935694454324235968155913963282642649968153284626154111478389914316765783434365458352785868895582488312334931317935669453447478936938533669921165437373741448378477391812779971528975478298688754939216421429251727555596481943322266289527996672856387648674166997731342558986575258793261986817177487197512282162964167151259485744835854547513341322647732662443512251886771887651614177679229984271191292374755915457372775856178539965131319568278252326242615151412772254257847413799811417287481321745372879513766235745347872632946776538173667371228977212143996391617974367923439923774388523845589769341351167311398787797583543434725374343611724379399566197432154146881344528319826434554239373666962546271299717743591225567564655511353255197516515213963862383762258959957474789718564758843367325794589886852413314713698911855183778978722558742329429867239261464773646389484318446574375323674136638452173815176732385468675215264736786242866295648997365412637499692817747937982628518926381939279935993712418938567488289246779458432179335139731952167527521377546376518126276