Start on the problem for day 3

Dependencies

• [2] XBZHQ672 Day 1 solution

Change contents

• file addition: day3.rs (----------)
  [2.7]
  + //use std::io;

  + use std::f64;

  +

  + fn spiral_ring(c: i64) -> i64 {

  + let f = c as f64;

  + ((f.sqrt() + 1.0) / 2.0).ceil() as i64

  + }

  +

  + fn ring_open(n: i64) -> i64 {

  + ring_d4(n - 1) + 1

  + }

  +

  + fn ring_d4(n: i64) -> i64 {

  + (n * 2 - 1).pow(2)

  + }

  +

  + fn ring_d3(n: i64) -> i64 {

  + (n * 2 - 1).pow(2) - 2 * (n - 1)

  + }

  +

  + fn main() {

  + println!("{}", ring_open(3));

  + }