Added day 6 code for part 1 and 2

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

day6/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "day6"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

day6/input

@@ -0,0 +1 @@
+1,4,3,3,1,3,1,1,1,2,1,1,1,4,4,1,5,5,3,1,3,5,2,1,5,2,4,1,4,5,4,1,5,1,5,5,1,1,1,4,1,5,1,1,1,1,1,4,1,2,5,1,4,1,2,1,1,5,1,1,1,1,4,1,5,1,1,2,1,4,5,1,2,1,2,2,1,1,1,1,1,5,5,3,1,1,1,1,1,4,2,4,1,2,1,4,2,3,1,4,5,3,3,2,1,1,5,4,1,1,1,2,1,1,5,4,5,1,3,1,1,1,1,1,1,2,1,3,1,2,1,1,1,1,1,1,1,2,1,1,1,1,2,1,1,1,1,1,1,4,5,1,3,1,4,4,2,3,4,1,1,1,5,1,1,1,4,1,5,4,3,1,5,1,1,1,1,1,5,4,1,1,1,4,3,1,3,3,1,3,2,1,1,3,1,1,4,5,1,1,1,1,1,3,1,4,1,3,1,5,4,5,1,1,5,1,1,4,1,1,1,3,1,1,4,2,3,1,1,1,1,2,4,1,1,1,1,1,2,3,1,5,5,1,4,1,1,1,1,3,3,1,4,1,2,1,3,1,1,1,3,2,2,1,5,1,1,3,2,1,1,5,1,1,1,1,1,1,1,1,1,1,2,5,1,1,1,1,3,1,1,1,1,1,1,1,1,5,5,1

day6/src/main.rs

@@ -0,0 +1,38 @@
+use std::{fs, env};
+
+fn read_input(path: &str) -> String {
+    return fs::read_to_string(path).expect("Cannot read file.");
+}
+
+fn parse_input(s: &str) -> Vec<i32> {
+    return s.replace("\n", "").split(",")
+        .filter_map(|e| e.parse::<i32>().ok()).collect();
+}
+
+fn smart_compute_x_days(v: &Vec<i32>, x: i32) -> i128 {
+    let mut l: Vec<i128> = vec![0;9];
+    for i in v {
+        l[*i as usize] += 1;
+    }
+
+    for _d in 1..=x {
+        let n = l[0];
+        for i in 1..9 {
+            l[i - 1] = l[i];
+        }
+        l[6] += n;
+        l[8] = n;
+    }
+    return l.iter().sum();
+}
+
+fn main() {
+    let args: Vec<String> = env::args().collect();
+    for arg in args.iter().skip(1) {
+        let vec_in = parse_input(&read_input(&arg));
+        println!("[{}]", &arg);
+        println!("\t[Part 1] => Answer is '{}'.", smart_compute_x_days(&vec_in, 80));
+        println!("\t[Part 2] => Answer is '{}'.", smart_compute_x_days(&vec_in, 256));
+    }
+}
+