Added day 16 code for part 1 and 2

Signed-off-by: Louis Vallat <louis@louis-vallat.xyz>

.gitlab-ci.yml

@@ -78,3 +78,8 @@ day-15:
   stage: build
   script:
     - cd day15; cargo run --release ./input
+
+day-16:
+  stage: build
+  script:
+    - cd day16; cargo run --release ./input

day16/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "day16"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

day16/input

@@ -0,0 +1 @@
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

day16/src/main.rs

@@ -0,0 +1,87 @@
+use std::{fs, env};
+
+#[derive(Debug)]
+struct Packet {
+    v: u8,
+    c: i64,
+    s: Vec<Packet>
+}
+
+fn read_input(path: &str) -> String {
+    return fs::read_to_string(path).expect("Cannot read file.");
+}
+
+fn parse_input(s: &str) -> Vec<bool> {
+    let s = s.lines().last().unwrap();
+    let mut x = vec![];
+    for c in s.chars() {
+        let v = c.to_digit(16).unwrap();
+        x.push((v & 0b1000) != 0);
+        x.push((v & 0b100) != 0);
+        x.push((v & 0b10) != 0);
+        x.push((v & 1) != 0);
+    }
+    return x;
+}
+
+fn get_int(v: &Vec<bool>) -> i64 {
+    return v.iter().fold(0, |acc, e| (acc << 1) + if *e { 1 } else { 0 });
+}
+
+fn get_packet(x: &mut Vec<bool>) -> Packet {
+    let v = get_int(&x.drain(0..3).collect()) as u8;
+    let t = get_int(&x.drain(0..3).collect()) as u8;
+    let c;
+    let mut s = vec![];
+    if t == 4 {
+        let mut i = vec![];
+        let mut w = true;
+        while w {
+            w = x.remove(0);
+            i.append(&mut x.drain(0..4).collect());
+        }
+
+        c = get_int(&i);
+    } else {
+        if x.remove(0) {
+            let n = get_int(&x.drain(0..11).collect());
+            for _i in 0..n { s.push(get_packet(x)); }
+        } else {
+            let mut n = get_int(&x.drain(0..15).collect()) as usize;
+            while n != 0 {
+                let b = x.len();
+                s.push(get_packet(x));
+                n -= b - x.len();
+            }
+        }
+        c = match t {
+            0 => { s.iter().fold(0, |acc, e| acc + e.c) }
+            1 => { s.iter().fold(1, |acc, e| acc * e.c) }
+            2 => { s.iter().fold(i64::MAX, |acc, e| if e.c < acc { e.c } else { acc }) }
+            3 => { s.iter().fold(i64::MIN, |acc, e| if e.c > acc { e.c } else { acc }) }
+            5 => { if s[0].c > s[1].c { 1 } else { 0 } }
+            6 => { if s[0].c < s[1].c { 1 } else { 0 } }
+            7 => { if s[0].c == s[1].c { 1 } else { 0 } }
+            _ => { panic!() }
+        };
+    }
+
+    return Packet { v, c, s };
+}
+
+fn get_version_sum(p: &Packet) -> u32 {
+    return p.v as u32 + p.s.iter().fold(0, |acc, s| acc + get_version_sum(s));
+}
+
+fn main() {
+    let args: Vec<String> = env::args().collect();
+    for arg in args.iter().skip(1) {
+        let input = read_input(&arg);
+        let mut x = parse_input(&input);
+        let p = get_packet(&mut x);
+        println!("[{}]", &arg);
+        println!("\t[Part 1] => Answer is '{}'.", get_version_sum(&p));
+        println!("\t[Part 2] => Answer is '{}'.", p.c);
+    }
+}
+