From 21dfc7f6309b76c8adff7baf52f0b6c9984c41e9 Mon Sep 17 00:00:00 2001
From: Johannes <jschaef@mail.uni-paderborn.de>
Date: Tue, 25 Dec 2018 14:32:32 +0100
Subject: [PATCH] day22 little speed improvement

---
 src/tasks/day22.rs | 34 ++++++++++++++++++++++++++++------
 1 file changed, 28 insertions(+), 6 deletions(-)

diff --git a/src/tasks/day22.rs b/src/tasks/day22.rs
index 73e8c5f..e6a7a2f 100644
--- a/src/tasks/day22.rs
+++ b/src/tasks/day22.rs
@@ -7,13 +7,14 @@ use std::time::Instant;
 pub fn both() {
     let start = Instant::now();
     let mut cave = Cave::create(3879, Node(8, 713, Torch));
-    println!("{:?}", Instant::now() - start);
-    let start = Instant::now();
+    println!("#{:?}", Instant::now() - start);
+    let x = Instant::now();
     println!("Sum of erosion indexes: {}", cave.erosion_sum());
-    println!("{:?}", Instant::now() - start);
-    let start = Instant::now();
+    println!("#{:?}", Instant::now() - x);
+    let x = Instant::now();
     println!("Shortest path length: {}", cave.shortest_path_length());
-    println!("{:?}", Instant::now() - start);
+    println!("#{:?}", Instant::now() - x);
+    println!("#Overall run time: {:?}", Instant::now() - start);
 }
 
 #[derive(PartialEq, Clone, Copy, Debug, Eq, Hash)]
@@ -37,7 +38,8 @@ impl Cave {
         if target.2 != Torch {
             panic!("A valid target point needs the torch equipped");
         }
-        let map = HashMap::with_capacity(target.0 * target.1);
+
+        let map = HashMap::with_capacity((target.0 + 1) * (target.1 + 1));
 
         Cave { map, target, depth }
     }
@@ -74,9 +76,17 @@ impl Cave {
     }
 
     fn shortest_path_length(&mut self) -> usize {
+        self.map.reserve(
+            std::cmp::max(self.target.0, self.target.1)
+                * std::cmp::max(self.target.0, self.target.1)
+                - self.map.len(),
+        );
         let start = Node(0, 0, Torch);
         let mut open: BinaryHeap<State> = BinaryHeap::new();
         let mut distances: HashMap<Node, usize> = HashMap::new();
+        // let mut rightmost = 0;
+        // let mut lowest = 0;
+        // let mut visited_counter = 0;
 
         distances.insert(start, 0);
         open.push(State {
@@ -86,8 +96,20 @@ impl Cave {
 
         // Examine the frontier with lower cost nodes first (min-heap)
         while let Some(State { cost, position }) = open.pop() {
+            // if position.0 > rightmost {
+            //     rightmost = position.0;
+            // }
+            // if position.1 > lowest {
+            //     lowest = position.1;
+            // }
+            // visited_counter += 1;
+
             // Alternatively we could have continued to find all shortest paths
             if position == self.target {
+                // println!(
+                //     "Visited {} nodes ({}, {})",
+                //     visited_counter, rightmost, lowest
+                // );
                 return cost;
             }