From beb7b447e97c49ad13f91c4a58913668573dd3c1 Mon Sep 17 00:00:00 2001
From: Henk Kalkwater <chris@netsoj.nl>
Date: Wed, 2 Dec 2020 18:22:20 +0100
Subject: [PATCH] Added day 2 part 2

---
 source/day2.d | 39 +++++++++++++++++++++++++++++++--------
 1 file changed, 31 insertions(+), 8 deletions(-)

diff --git a/source/day2.d b/source/day2.d
index d73dc5b..8bf84af 100644
--- a/source/day2.d
+++ b/source/day2.d
@@ -1,11 +1,20 @@
 import std.algorithm;
 import std.format;
+import std.functional;
 import std.stdio;
 
 
 import dayutil;
 
-bool isPasswordValid(T)(T line) {
+void run(string[] args) {
+	ulong count = parts!ulong(args,
+			() => stdin.byLine.count!(l => isPasswordValid1(l)),
+			() => stdin.byLine.count!(l => isPasswordValid2(l)));
+	writeln(count);
+}
+
+/// Part 1
+bool isPasswordValid1(T)(T line) {
 	int min, max;
 	char c;
 	string password;
@@ -14,14 +23,28 @@ bool isPasswordValid(T)(T line) {
 	return min <= charCount && charCount <= max;
 }
 
-void run(string[] args) {
-	ulong count = stdin.byLine
-		.count!(l => isPasswordValid(l));
-	writeln(count);
+unittest {
+	assert(isPasswordValid1("1-3 a: abcde") == true);
+	assert(isPasswordValid1("1-3 b: cdefg") == false);
+	assert(isPasswordValid1("2-9 c: ccccccccc") == true);
+}
+
+/// Part 2
+bool isPasswordValid2(T)(T line) {
+	int min, max;
+	char c;
+	string password;
+	line.formattedRead("%d-%d %c: %s", min, max, c, password);
+	// 1 2 | R
+	// T T | F
+	// T F | T
+	// F T | T
+	// F F | F
+	return (password[min - 1] == c) != (password[max - 1] == c);
 }
 
 unittest {
-	assert(isPasswordValid("1-3 a: abcde") == true);
-	assert(isPasswordValid("1-3 b: cdefg") == false);
-	assert(isPasswordValid("2-9 c: ccccccccc") == true);
+	assert(isPasswordValid2("1-3 a: abcde") == true);
+	assert(isPasswordValid2("1-3 b: cdefg") == false);
+	assert(isPasswordValid2("2-9 c: ccccccccc") == false);
 }