added day10

Signed-off-by: Philip Molares <philip.molares@udo.edu>

day10/Cargo.lock

+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+[[package]]
+name = "day10"
+version = "0.1.0"

day10/Cargo.toml

+[package]
+name = "day10"
+version = "0.1.0"
+authors = ["Philip Molares <philip.molares@udo.edu>"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

day10/input.txt

+95
+43
+114
+118
+2
+124
+120
+127
+140
+21
+66
+103
+102
+132
+136
+93
+59
+131
+32
+9
+20
+141
+94
+109
+143
+142
+65
+73
+27
+83
+133
+104
+60
+110
+89
+29
+78
+49
+76
+16
+34
+17
+105
+98
+15
+106
+4
+57
+1
+67
+71
+14
+92
+39
+68
+125
+113
+115
+26
+33
+61
+45
+46
+11
+99
+7
+25
+130
+42
+3
+10
+54
+44
+139
+50
+8
+58
+86
+64
+77
+35
+79
+72
+36
+80
+126
+28
+123
+119
+51
+22
\ No newline at end of file

day10/src/main.rs

+use std::fs::File;
+use std::io::{self, prelude::*, BufReader};
+
+fn calculate_differences(input: &Vec<i64>) -> (i64, i64, i64) {
+    let mut ones = 0;
+    let mut twos = 0;
+    let mut threes = 0;
+
+    let mut joltage = 0;
+
+    for number in input {
+        match number - joltage {
+            0 => (),
+            1 => ones += 1,
+            2 => twos += 1,
+            3 => threes += 1,
+            _ => unimplemented!()
+        }
+        joltage = *number;
+    }
+
+    (ones, twos, threes)
+}
+
+fn part_2(input: &Vec<i64>) -> i64 {
+    let mut slices = vec![];
+    let mut current_slice = vec![];
+
+    for window in input.windows(2) {
+        match window[1] - window[0] {
+            1 => current_slice.push(window[0]),
+            3 => {
+                current_slice.push(window[0]);
+                slices.push(current_slice);
+                current_slice = vec![];
+            }
+            _ => (),
+        }
+    }
+
+    slices
+        .iter()
+        .map(|slice| match slice.len() {
+            1 => 1,
+            2 => 1,
+            3 => 2,
+            4 => 4,
+            5 => 7,
+            _ => panic!("unexpected slice of size N > 5 consecutive 1-diff elements"),
+        })
+        .product()
+
+}
+
+fn main() -> io::Result<()> {
+    println!("Advent of Code 2020 – Day 10:");
+
+    let file = File::open("input.txt")?;
+    let reader = BufReader::new(file);
+
+    let mut input = reader
+        .lines()
+        .map(|l| l.unwrap().parse::<i64>().unwrap())
+        .collect::<Vec<i64>>();
+
+    input.sort();
+    input.insert(0, 0);
+    input.push(*input.last().unwrap() + 3);
+
+    let (ones, _, threes) = calculate_differences(&input);
+
+    println!("Answer Part 1: {}", ones*threes);
+
+    let answer2 = part_2(&input);
+
+    println!("Answer Part 2: {}", answer2);
+    
+
+    Ok(())
+}