From 6901d71abb97414000a13b3421801e2ee133286f Mon Sep 17 00:00:00 2001
From: Alpha Chen <alpha.chen@gmail.com>
Date: Mon, 11 Dec 2017 21:42:42 -0800
Subject: [PATCH] [2017][rust][5.x]

---
 2017/rust/src/day_04.rs |  3 +++
 2017/rust/src/day_05.rs | 25 +++++++++++++++++++++++++
 2017/rust/src/main.rs   |  3 ++-
 3 files changed, 30 insertions(+), 1 deletion(-)
 create mode 100644 2017/rust/src/day_05.rs

diff --git a/2017/rust/src/day_04.rs b/2017/rust/src/day_04.rs
index 3033363..be85a75 100644
--- a/2017/rust/src/day_04.rs
+++ b/2017/rust/src/day_04.rs
@@ -1,6 +1,7 @@
 use std::collections::HashSet;
 use failure::Error;
 
+#[allow(dead_code)]
 pub fn solve(input: &str) -> Result<String, Error> {
     Ok(input
         .trim()
@@ -11,11 +12,13 @@ pub fn solve(input: &str) -> Result<String, Error> {
         .to_string())
 }
 
+#[allow(dead_code)]
 struct Passphrase {
     words: String,
 }
 
 impl Passphrase {
+    #[allow(dead_code)]
     fn is_valid(&self) -> bool {
         let mut words = HashSet::new();
         !self.words
diff --git a/2017/rust/src/day_05.rs b/2017/rust/src/day_05.rs
new file mode 100644
index 0000000..a972da3
--- /dev/null
+++ b/2017/rust/src/day_05.rs
@@ -0,0 +1,25 @@
+use std::collections::HashMap;
+use std::collections::hash_map::Entry;
+use failure::*;
+
+pub fn solve(input: &str) -> Result<String, Error> {
+    let mut jumps: HashMap<isize, isize> = input
+        .trim()
+        .lines()
+        .enumerate()
+        .map(|(i,x)| x.parse().map(|x| (i as isize, x)))
+        .collect::<Result<_,_>>()?;
+    let mut pc = 0;
+    let mut steps = 0;
+    while let Entry::Occupied(mut entry) = jumps.entry(pc) {
+        let offset = entry.get_mut();
+        pc += *offset;
+        if *offset >= 3 {
+            *offset -= 1;
+        } else {
+            *offset += 1;
+        }
+        steps += 1;
+    }
+    Ok(steps.to_string())
+}
diff --git a/2017/rust/src/main.rs b/2017/rust/src/main.rs
index a2983c8..bc88755 100644
--- a/2017/rust/src/main.rs
+++ b/2017/rust/src/main.rs
@@ -12,6 +12,7 @@ mod day_01;
 mod day_02;
 mod day_03;
 mod day_04;
+mod day_05;
 
 fn main() {
     if let Err(e) = run() {
@@ -23,7 +24,7 @@ fn run() -> Result<(), Error> {
     let mut input = String::new();
     io::stdin().read_to_string(&mut input)?;
 
-    let solution = day_04::solve(&input)?;
+    let solution = day_05::solve(&input)?;
     println!("{}", solution);
 
     Ok(())