From 02693c741931fd74bf7ba3e1c00799ec5db583f2 Mon Sep 17 00:00:00 2001
From: Bill Ewanick <bill@ewanick.com>
Date: Wed, 15 Nov 2023 17:05:27 -0500
Subject: [PATCH] L33t code 841, by David Schindler

---
 flake.nix           |  2 ++
 src/l33tcode/841.go | 41 +++++++++++++++++++++++++++++++++++++++++
 src/l33tcode/841.hs |  0
 3 files changed, 43 insertions(+)
 create mode 100644 src/l33tcode/841.go
 create mode 100644 src/l33tcode/841.hs

diff --git a/flake.nix b/flake.nix
index b2e17b2..6cc9cd5 100644
--- a/flake.nix
+++ b/flake.nix
@@ -78,6 +78,8 @@
         ] ++ (with pkgs; [
           # Scripts
           clean
+
+          go
         ]);
 
         shellHook = ''
diff --git a/src/l33tcode/841.go b/src/l33tcode/841.go
new file mode 100644
index 0000000..0b258b2
--- /dev/null
+++ b/src/l33tcode/841.go
@@ -0,0 +1,41 @@
+package main
+
+import "fmt"
+
+func main() {
+	res := canVisitAllRooms([][]int{{1}, {2}, {}})
+	fmt.Printf("%+v\n", res)
+}
+
+func canVisitAllRooms(rooms [][]int) bool {
+	if len(rooms) > 0 && len(rooms[0]) == 0 {
+			return false
+	}
+
+	keys := getAllKeys(0, make(map[int]struct{}), rooms)
+	keys[0] = struct{}{}    
+
+	for i := 0; i < len(rooms); i++ {
+			if _, ok := keys[i]; !ok {
+					return false
+			}
+	}
+	return true
+}
+
+func getAllKeys(index int, seen map[int]struct{}, rooms [][]int) map[int]struct{} {
+	keys := map[int]struct{}{}
+
+	for j := 0; j < len(rooms[index]); j++ {
+			if _, ok := keys[rooms[index][j]]; ok {
+					continue
+			}
+			keys[rooms[index][j]] = struct{}{}
+			insideKeys := getAllKeys(j, keys, rooms)
+			for k := range insideKeys {
+					keys[k] = struct{}{}
+			}
+	}
+	
+	return keys
+}
diff --git a/src/l33tcode/841.hs b/src/l33tcode/841.hs
new file mode 100644
index 0000000..e69de29