Solve day 1 for 2020

Dependencies

• [2] IVWB6VSK Add solutions for 2019 day 3.

Change contents

• replacement in 2019/day3.rs at line 70
  [2.1334]→[2.1334:1346](∅→∅)
  − })
  [2.1334]

  [2.1346]
  + })
• file addition: 2020 (d--r------)
  [1.0]
• file addition: day1.rs (----------)
  [0.17]
  + use std::convert::TryInto;

  + use std::env;

  +

  + struct Ixs {

  + ixs: Vec<usize>,

  + max: usize,

  + }

  +

  + impl Iterator for Ixs {

  + type Item=Vec<usize>;

  + fn next(&mut self) -> Option<Self::Item> {

  + let mut ixix = self.ixs.len() - 1;

  + loop {

  + let v = self.ixs[ixix] + 1;

  + if v > self.max {

  + if ixix == 0 {

  + return None;

  + } else {

  + ixix = ixix - 1;

  + }

  + } else {

  + for ixiy in ixix .. self.ixs.len() {

  + self.ixs[ixiy] = v;

  + };

  + return Some(self.ixs.clone())

  + }

  + }

  + }

  + }

  +

  + impl Ixs {

  + fn new(count: usize, max: usize) -> Self {

  + let mut r = Ixs { ixs: Vec::new(), max: max, };

  + r.ixs.resize(count, 0);

  + r

  + }

  + }

  +

  + fn find2020(i: &Vec<i64>, n: i64) -> i64 {

  + for ixs in Ixs::new(n.try_into().unwrap(), i.len() - 1) {

  + if ixs.iter().map(|ix| i[*ix] ).sum::<i64>() == 2020 {

  + return ixs.iter().map(|ix| i[*ix] ).product();

  + }

  + }

  + panic!("Not found!")

  + }

  +

  + fn main() {

  + let args: Vec<_> = env::args().collect();

  + let numbers: Vec<i64> = std::fs::read_to_string(&args[1])

  + .unwrap()

  + .split_whitespace()

  + .map(|l| l.parse().unwrap())

  + .collect();

  + println!("{}", find2020(&numbers, args[2].parse().unwrap()));

  + }