From ca275c703e4d73718537f16f0117bdd12f6d3ab7 Mon Sep 17 00:00:00 2001
From: henine <why@no.com>
Date: Thu, 10 Dec 2020 09:36:37 +0100
Subject: [PATCH] day10

---
 day10/Cargo.toml  |   9 ++++
 day10/input       | 106 ++++++++++++++++++++++++++++++++++++++++++++++
 day10/src/main.rs |  52 +++++++++++++++++++++++
 day10/test        |  31 ++++++++++++++
 4 files changed, 198 insertions(+)
 create mode 100644 day10/Cargo.toml
 create mode 100644 day10/input
 create mode 100644 day10/src/main.rs
 create mode 100644 day10/test

diff --git a/day10/Cargo.toml b/day10/Cargo.toml
new file mode 100644
index 0000000..476bec7
--- /dev/null
+++ b/day10/Cargo.toml
@@ -0,0 +1,9 @@
+[package]
+name = "day10"
+version = "0.1.0"
+authors = ["henine <why@no.com>"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
diff --git a/day10/input b/day10/input
new file mode 100644
index 0000000..89adc49
--- /dev/null
+++ b/day10/input
@@ -0,0 +1,106 @@
+66
+7
+73
+162
+62
+165
+157
+158
+137
+125
+138
+59
+36
+40
+94
+95
+13
+35
+136
+96
+156
+155
+24
+84
+42
+171
+142
+3
+104
+149
+83
+129
+19
+122
+68
+103
+74
+118
+20
+110
+54
+127
+88
+31
+135
+26
+126
+2
+51
+91
+16
+65
+128
+119
+67
+48
+111
+29
+49
+12
+132
+17
+41
+166
+75
+146
+50
+30
+1
+164
+112
+34
+18
+72
+97
+145
+11
+117
+58
+78
+152
+90
+172
+163
+89
+107
+45
+37
+79
+159
+141
+105
+10
+115
+69
+170
+25
+100
+80
+4
+85
+169
+106
+57
+116
+23
diff --git a/day10/src/main.rs b/day10/src/main.rs
new file mode 100644
index 0000000..f0e909c
--- /dev/null
+++ b/day10/src/main.rs
@@ -0,0 +1,52 @@
+use std::fs::File;
+use std::io::{BufRead, BufReader};
+use std::string::String;
+
+fn main() {
+    let file = match File::open("input") {
+        Ok(file) => file,
+        Err(e) => panic!(e)
+    };
+
+    let input_buffer = BufReader::new(&file);
+    let lines = input_buffer.lines();
+
+    let mut adapters: Vec<u32> = lines
+        .map(Result::unwrap)
+        .map(|x: String| x.trim().to_string())
+        .map(|x| x.parse::<u32>().unwrap())
+        .collect();
+
+    adapters.sort();
+
+    let mut hist = [0, 0, 1];
+    let mut prev = 0;
+    for adapter in adapters.iter() {
+        hist[(adapter - prev - 1) as usize] += 1;
+        prev = *adapter;
+    }
+    println!("{:?}", hist);
+
+    println!("{}", hist[0] * hist[2]);
+
+    adapters.reverse();
+
+    let mut path_counts = Vec::with_capacity(adapters.len());
+    path_counts.push(1 as u64);
+    for _i in 1..adapters.len() { path_counts.push(0 as u64) };
+
+    for adapter_i in 1..adapters.len() {
+        let adapter = adapters[adapter_i];
+        path_counts[adapter_i] =
+            if adapter_i >= 1 && adapters[adapter_i - 1] - adapter <= 3 { path_counts[adapter_i - 1] } else { 0 } +
+            if adapter_i >= 2 && adapters[adapter_i - 2] - adapter <= 3 { path_counts[adapter_i - 2] } else { 0 } +
+            if adapter_i >= 3 && adapters[adapter_i - 3] - adapter <= 3 { path_counts[adapter_i - 3] } else { 0 }
+    }
+
+    let count =
+        if adapters[adapters.len() - 1] <= 3 { path_counts[adapters.len() - 1] } else { 0 } +
+            if adapters[adapters.len() - 2] <= 3 { path_counts[adapters.len() - 2] } else { 0 } +
+            if adapters[adapters.len() - 3] <= 3 { path_counts[adapters.len() - 3] } else { 0 };
+
+    println!("{}", count);
+}
diff --git a/day10/test b/day10/test
new file mode 100644
index 0000000..be5c492
--- /dev/null
+++ b/day10/test
@@ -0,0 +1,31 @@
+28
+33
+18
+42
+31
+14
+46
+20
+48
+47
+24
+23
+49
+45
+19
+38
+39
+11
+1
+32
+25
+35
+8
+17
+7
+9
+4
+2
+34
+10
+3
\ No newline at end of file