From 8ab440a765cc9502d5ab103f54782d0f2e41125d Mon Sep 17 00:00:00 2001
From: Louis Vallat <louis@louis-vallat.xyz>
Date: Fri, 24 Dec 2021 23:17:06 +0100
Subject: [PATCH] Added day 17 code for part 1 and 2

Signed-off-by: Louis Vallat <louis@louis-vallat.xyz>
---
 .gitlab-ci.yml    |  5 ++++
 day17/Cargo.toml  |  8 ++++++
 day17/input       |  1 +
 day17/src/main.rs | 67 +++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 81 insertions(+)
 create mode 100644 day17/Cargo.toml
 create mode 100644 day17/input
 create mode 100644 day17/src/main.rs

diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 72daea1..16b85d0 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -83,3 +83,8 @@ day-16:
   stage: build
   script:
     - cd day16; cargo run --release ./input
+
+day-17:
+  stage: build
+  script:
+    - cd day17; cargo run --release ./input
diff --git a/day17/Cargo.toml b/day17/Cargo.toml
new file mode 100644
index 0000000..e483073
--- /dev/null
+++ b/day17/Cargo.toml
@@ -0,0 +1,8 @@
+[package]
+name = "day17"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
diff --git a/day17/input b/day17/input
new file mode 100644
index 0000000..6b9ce9e
--- /dev/null
+++ b/day17/input
@@ -0,0 +1 @@
+target area: x=25..67, y=-260..-200
diff --git a/day17/src/main.rs b/day17/src/main.rs
new file mode 100644
index 0000000..cfc91bc
--- /dev/null
+++ b/day17/src/main.rs
@@ -0,0 +1,67 @@
+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) -> ((i32, i32), (i32, i32)) {
+    let v = s.trim_end_matches("\n")
+        .split_once("x=").unwrap()
+        .1.split_once(", y=").unwrap();
+    let s = v.0.split_once("..").unwrap();
+    let e = v.1.split_once("..").unwrap();
+    return ((s.0.parse().unwrap(), s.1.parse().unwrap()),
+            (e.0.parse().unwrap(), e.1.parse().unwrap()));
+}
+
+fn has_crossed(p: &(i32, i32), z: &((i32, i32), (i32, i32))) -> bool {
+    return p.0 > z.0.1 || p.1 < z.1.0;
+}
+
+fn is_in(p: &(i32, i32), z: &((i32, i32), (i32, i32))) -> bool {
+    return p.0 >= z.0.0 && p.0 <= z.0.1 && p.1 >= z.1.0 && p.1 <= z.1.1;
+}
+
+fn compute_trajectory(mut v: (i32, i32), z: &((i32, i32), (i32, i32)), t: &mut Vec<(i32, i32)>) {
+    let mut l = t.last().unwrap_or(&(0, 0)).to_owned();
+    while !(has_crossed(&l, z) || is_in(&l, z)) {
+        l.0 += v.0;
+        l.1 += v.1;
+        v.0 += if v.0 > 0 { -1 } else if v.0 < 0 { 1 } else { 0 };
+        v.1 -= 1;
+        t.push(l);
+    }
+}
+
+fn get_max_y(v: &Vec<(i32, i32)>) -> i32 {
+    return v.iter().fold(i32::MIN, |acc, e| if e.1 > acc { e.1 } else { acc });
+}
+
+fn get_optimized_trajectory(z: &((i32, i32), (i32, i32))) -> (i32, usize) {
+    let mut v = vec![];
+    for i in 0..700 {
+        for j in -300..700 {
+            let mut b = vec![];
+            compute_trajectory((i, j), z, &mut b);
+            if is_in(b.last().unwrap(), z) { v.push(b); }
+        }
+    }
+    let mut max = i32::MIN;
+    for i in v.clone() {
+        let m = get_max_y(&i);
+        if m > max { max = m; }
+    }
+    return (max, v.len());
+}
+
+fn main() {
+    let args: Vec<String> = env::args().collect();
+    for arg in args.iter().skip(1) {
+        let input = read_input(&arg);
+        let vec_in = parse_input(&input);
+        let a = get_optimized_trajectory(&vec_in);
+        println!("[{}]", &arg);
+        println!("\t[Part 1] => Answer is '{}'.", a.0);
+        println!("\t[Part 2] => Answer is '{}'.", a.1);
+    }
+}