From 159c41390cd89179b09e4bbd34a441d5730fcbbe Mon Sep 17 00:00:00 2001
From: Ishan Jain <contact@ishanjain.me>
Date: Sun, 3 Dec 2023 14:21:15 +0530
Subject: [PATCH] day3: optimized p2 and p1

---
 src/day3/1.rs       |  1 -
 src/day3/2.rs       | 38 ++++++++++++++++++++------------------
 src/day3/sample.txt |  2 +-
 3 files changed, 21 insertions(+), 20 deletions(-)

diff --git a/src/day3/1.rs b/src/day3/1.rs
index 458b3ae..73f0d52 100644
--- a/src/day3/1.rs
+++ b/src/day3/1.rs
@@ -43,7 +43,6 @@ fn process(data: &[u8]) -> u64 {
             }
 
             let mut valid = false;
-
             'outer: for (a, b) in DIRS.iter() {
                 let x = i as i32 + a;
 
diff --git a/src/day3/2.rs b/src/day3/2.rs
index 1584b38..1c35d62 100644
--- a/src/day3/2.rs
+++ b/src/day3/2.rs
@@ -1,6 +1,6 @@
 #![feature(test)]
 
-use std::collections::{HashMap, HashSet};
+use std::collections::HashSet;
 extern crate test;
 
 const INPUTS: [&[u8]; 2] = [
@@ -30,13 +30,10 @@ fn process(data: &[u8]) -> u64 {
     let m = grid.len();
     let n = grid[0].len();
 
-    let mut map = HashMap::with_capacity(200);
-
+    let mut set = HashSet::with_capacity(2);
     for i in 0..m {
         for j in 0..n {
-            let c = grid[i][j];
-
-            if c != b'*' {
+            if grid[i][j] != b'*' {
                 continue;
             }
 
@@ -65,26 +62,31 @@ fn process(data: &[u8]) -> u64 {
                     ey += 1;
                 }
 
-                let num = String::from_utf8_lossy(&grid[x][sy..ey])
-                    .parse::<u64>()
-                    .unwrap();
+                // only insert valid parts in this
+                if set.len() < 2 {
+                    set.insert((parse(&grid[x][sy..ey]), sy, ey, x));
+                }
+            }
 
-                map.entry((i, j))
-                    .or_insert_with(HashSet::new)
-                    .insert((num, x, sy, ey));
+            if set.len() == 2 {
+                total += set.drain().fold(1, |a, (x, _, _, _)| a * x);
+            } else {
+                set.clear();
             }
         }
     }
 
-    for v in map.into_values() {
-        if v.len() < 2 {
-            continue;
-        }
+    total
+}
 
-        total += v.into_iter().fold(1, |a, (b, _, _, _)| a * b);
+fn parse(b: &[u8]) -> u64 {
+    let mut output = 0;
+
+    for (i, v) in b.iter().enumerate() {
+        output += 10u64.pow(b.len() as u32 - i as u32 - 1) * ((v - b'0') as u64);
     }
 
-    total
+    output
 }
 
 fn main() {
diff --git a/src/day3/sample.txt b/src/day3/sample.txt
index 624ea4f..b20187f 100644
--- a/src/day3/sample.txt
+++ b/src/day3/sample.txt
@@ -7,4 +7,4 @@
 ..592.....
 ......755.
 ...$.*....
-.664.598..
\ No newline at end of file
+.664.598..