From 86a723beebcd2710d648c355d52bd96a5344f041 Mon Sep 17 00:00:00 2001
From: Julien Dessaux
Date: Sun, 12 Dec 2021 17:34:37 +0100
Subject: Added solutions for 12th day: caves pathing

---
 2021/12/second.go | 82 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 82 insertions(+)
 create mode 100644 2021/12/second.go

(limited to '2021/12/second.go')

diff --git a/2021/12/second.go b/2021/12/second.go
new file mode 100644
index 0000000..5350060
--- /dev/null
+++ b/2021/12/second.go
@@ -0,0 +1,82 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"strings"
+)
+
+type cave struct {
+	name  string
+	big   bool
+	leafs []int // index in caves array
+}
+
+var (
+	caves = []cave{cave{name: "start"}, cave{name: "end"}}
+	score = 0
+)
+
+const (
+	START = 0
+	END   = 1
+)
+
+func getIdOrAdd(name string) int {
+	for i, v := range caves {
+		if v.name == name {
+			return i
+		}
+	}
+	caves = append(caves, cave{
+		name: name,
+		big:  name[0] >= 'A' && name[0] <= 'Z',
+	})
+	return len(caves) - 1
+}
+
+func contains(id int, passed []int) bool {
+	for _, v := range passed {
+		if v == id {
+			return true
+		}
+	}
+	return false
+}
+
+func parcours(id int, passed []int, doublePass bool) {
+	if !caves[id].big {
+		if contains(id, passed) {
+			if doublePass {
+				return
+			} else {
+				doublePass = true
+			}
+		} else {
+			passed = append(passed, id)
+		}
+	}
+	for _, v := range caves[id].leafs {
+		if v == END {
+			score++
+			continue
+		} else if v == START {
+			continue
+		}
+		parcours(v, passed, doublePass)
+	}
+}
+
+func main() {
+	scanner := bufio.NewScanner(os.Stdin)
+	for scanner.Scan() {
+		line := strings.Split(scanner.Text(), "-")
+		a := getIdOrAdd(line[0])
+		b := getIdOrAdd(line[1])
+		caves[a].leafs = append(caves[a].leafs, b)
+		caves[b].leafs = append(caves[b].leafs, a)
+	}
+	parcours(START, nil, false)
+	fmt.Println(score)
+}
-- 
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