From 9ae4e6d3fa866ead1e6188c588063ecca583a6ad Mon Sep 17 00:00:00 2001
From: Joseph Chamochumbi <sephxd1234@gmail.com>
Date: Wed, 9 Nov 2022 17:38:00 +0100
Subject: [PATCH] feat: 2021 day 12, part two with Swift

---
 2021/swift/day-12.swift | 40 +++++++++++++++++++++++++++++++++-------
 1 file changed, 33 insertions(+), 7 deletions(-)

diff --git a/2021/swift/day-12.swift b/2021/swift/day-12.swift
index 915ea88..9c243f0 100644
--- a/2021/swift/day-12.swift
+++ b/2021/swift/day-12.swift
@@ -2,7 +2,7 @@ import Foundation
 
 let filename = "../input/day-12.in"
 
-func search(_ root: String, _ adj: [String: [String]], _ history: Set<String>, _ acc: [String]) -> [String] {
+func search(_ root: String, _ adj: [String: [String]], _ history: Set<String>, _ acc: [String], _ allow: String? = nil) -> [String] {
     let paths = acc.map {
         input in
         var next = input
@@ -20,13 +20,26 @@ func search(_ root: String, _ adj: [String: [String]], _ history: Set<String>, _
                 continue
             }
 
-            if node.lowercased() == node {
-                visited.insert(node)
+            if allow == nil {
+                if node.lowercased() == node {
+                    visited.insert(node)
+                }
+
+                let localResult = search(node, adj, visited, paths)
+
+                result.append(contentsOf: localResult)
+            } else {
+                if node == allow {
+                    let localResult = search(node, adj, visited, paths)
+                    result.append(contentsOf: localResult)
+                } else {
+                    if node.lowercased() == node {
+                        visited.insert(node)
+                    }
+                    let localResult = search(node, adj, visited, paths, allow)
+                    result.append(contentsOf: localResult)
+                }
             }
-
-            let localResult = search(node, adj, visited, paths)
-
-            result.append(contentsOf: localResult)
         }
 
         return result
@@ -53,6 +66,19 @@ func main() {
         let partOne = search("start", adj, Set(), ["start"])
 
         print("Part one:", partOne.count)
+
+        let smallCaves = adj.keys.filter { $0.lowercased() == $0 }.filter { $0 != "start" }
+
+        var partTwo = Set<String>()
+
+        for cave in smallCaves {
+            let result = search("start", adj, Set(), ["start"], cave)
+
+            partTwo.formUnion(result)
+        }
+
+        print("Part two:", partTwo.count)
+
     } catch {
         print(error)
     }