From 9abb60642c5c7ea61f26fd9690a2f265182ddf4d Mon Sep 17 00:00:00 2001
From: Wesley Moore <wes@wezm.net>
Date: Sat, 9 Dec 2017 14:10:47 +1000
Subject: [PATCH] Add day 4 part 2 solution

---
 2017/day/4/src/main.rs | 51 +++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 50 insertions(+), 1 deletion(-)

diff --git a/2017/day/4/src/main.rs b/2017/day/4/src/main.rs
index a5c0089..9b22ac1 100644
--- a/2017/day/4/src/main.rs
+++ b/2017/day/4/src/main.rs
@@ -11,7 +11,17 @@ fn main() {
         .filter(|valid| *valid == true)
         .count();
 
-    println!("{}", valid);
+    println!("Part 1: {}", valid);
+
+    let file = File::open("input").expect("unable to open input file");
+    let reader = BufReader::new(file);
+
+    let valid = reader.lines()
+        .map(|line| passphrase_is_valid_part2(&line.unwrap()))
+        .filter(|valid| *valid == true)
+        .count();
+
+    println!("Part 2: {}", valid);
 }
 
 fn passphrase_is_valid(passphrase: &str) -> bool {
@@ -19,6 +29,15 @@ fn passphrase_is_valid(passphrase: &str) -> bool {
     !passphrase.split_whitespace().any(|word| seen.insert(word) == false)
 }
 
+fn passphrase_is_valid_part2(passphrase: &str) -> bool {
+    let mut seen = HashSet::new();
+    !passphrase.split_whitespace().any(|word| {
+        let mut sorted_chars = word.chars().collect::<Vec<_>>();
+        sorted_chars.sort();
+        seen.insert(sorted_chars) == false
+    })
+}
+
 // aa bb cc dd ee is valid.
 #[test]
 fn test_example1() {
@@ -36,3 +55,33 @@ fn test_example2() {
 fn test_example3() {
     assert_eq!(passphrase_is_valid("aa bb cc dd aaa"), true)
 }
+
+// abcde fghij is a valid passphrase.
+#[test]
+fn test_example1_part2() {
+    assert_eq!(passphrase_is_valid_part2("abcde fghij "), true)
+}
+
+// abcde xyz ecdab is not valid - the letters from the third word can be rearranged to form the first word.
+#[test]
+fn test_example2_part2() {
+    assert_eq!(passphrase_is_valid_part2("abcde xyz ecdab"), false)
+}
+
+// a ab abc abd abf abj is a valid passphrase, because all letters need to be used when forming another word.
+#[test]
+fn test_example3_part2() {
+    assert_eq!(passphrase_is_valid_part2("a ab abc abd abf abj"), true)
+}
+
+// iiii oiii ooii oooi oooo is valid.
+#[test]
+fn test_example4_part2() {
+    assert_eq!(passphrase_is_valid_part2("iiii oiii ooii oooi oooo"), true)
+}
+
+// oiii ioii iioi iiio is not valid - any of these words can be rearranged to form any other word.
+#[test]
+fn test_example5_part2() {
+    assert_eq!(passphrase_is_valid_part2("oiii ioii iioi iiio"), false)
+}