From 6578d5123f317500fd08bc1966db6fcb3d85ebef Mon Sep 17 00:00:00 2001
From: Brian Buller <brian@bullercodeworks.com>
Date: Thu, 28 Dec 2023 13:48:29 -0600
Subject: [PATCH] 2023 Complete!

---
 2023/day25/main.go   | 181 +++++++++++++++++++++++++++++++++++++++++--
 2023/day25/testinput |  13 ++++
 helpers/queue.go     |  10 +++
 3 files changed, 196 insertions(+), 8 deletions(-)
 create mode 100644 2023/day25/testinput

diff --git a/2023/day25/main.go b/2023/day25/main.go
index 7146225..6c1f430 100644
--- a/2023/day25/main.go
+++ b/2023/day25/main.go
@@ -2,21 +2,186 @@ package main
 
 import (
 	"fmt"
+	"math/rand"
+	"strings"
 
 	h "git.bullercodeworks.com/brian/adventofcode/helpers"
 )
 
+type component struct {
+	id          string
+	connections map[string]component
+	conns       map[string]bool
+}
+
+type components struct {
+	all   map[string]component
+	edges []connections
+}
+
+type connections struct {
+	from, to string
+	track    []string
+}
+
 func main() {
-	inp := h.StdinToStringSlice()
-	part1(inp)
-	fmt.Println()
-	part2(inp)
+	lines := h.StdinToStringSlice()
+
+	var comps components
+	var edges []connections
+	var counter int
+	var tries int
+	for tries < 100 {
+		counter = 0
+		for {
+			counter++
+			compsS := components{all: make(map[string]component)}
+			for _, line := range lines {
+				connect(&compsS, line)
+			}
+			cc := minCut(compsS)
+			cuts := len(cc.edges)
+			edges = cc.edges
+			comps = compsS
+			if cuts == 3 {
+				break
+			}
+			if counter >= 100 {
+				break
+			}
+		}
+		tries++
+		if counter < 100 {
+			break
+		}
+	}
+
+	total := cutInGroups(&comps, edges)
+	fmt.Println(total)
 }
 
-func part1(inp []string) {
-	fmt.Println("# Part 1")
+func connect(comps *components, line string) {
+	split := strings.Split(line, ": ")
+	nodeName := split[0]
+	connectionsNames := strings.Split(split[1], " ")
+
+	node := component{id: nodeName, connections: make(map[string]component), conns: make(map[string]bool)}
+	if _, ok := comps.all[nodeName]; !ok {
+		comps.all[nodeName] = node
+	}
+	for _, neighborName := range connectionsNames {
+		neighbor := component{id: neighborName, connections: make(map[string]component), conns: make(map[string]bool)}
+		if _, ok := comps.all[neighborName]; !ok {
+			comps.all[neighborName] = neighbor
+		}
+		comps.all[nodeName].connections[neighborName] = neighbor
+		comps.all[nodeName].conns[neighborName] = true
+		comps.all[neighborName].connections[nodeName] = node
+		comps.all[neighborName].conns[nodeName] = true
+		comps.edges = append(comps.edges, connections{
+			from:  nodeName,
+			to:    neighborName,
+			track: []string{nodeName, neighborName},
+		})
+	}
 }
 
-func part2(inp []string) {
-	fmt.Println("# Part 2")
+func minCut(comps components) components {
+	cc := components{
+		all:   make(map[string]component),
+		edges: comps.edges,
+	}
+	for key, val := range comps.all {
+		cc.all[key] = val
+	}
+
+	for len(cc.all) > 2 {
+		u, v := randomComps(&cc)
+		contract(&cc, u, v)
+	}
+
+	return cc
+}
+
+func randomComps(comps *components) (component, component) {
+	randomN := rand.Intn(len(comps.edges))
+	edge := comps.edges[randomN]
+	comps.edges = append(comps.edges[:randomN], comps.edges[randomN+1:]...)
+	randCorn := rand.Intn(2)
+	var nameU, nameV string
+	if randCorn == 0 {
+		nameU = edge.from
+		nameV = edge.to
+	} else {
+		nameU = edge.to
+		nameV = edge.from
+	}
+	u, v := comps.all[nameU], comps.all[nameV]
+	return u, v
+}
+
+func contract(comps *components, u component, v component) {
+	delete(comps.all, v.id)
+	delete(comps.all[u.id].connections, v.id)
+	for _, node := range comps.all {
+		if _, ok := node.connections[v.id]; ok {
+			delete(node.connections, v.id)
+			node.connections[u.id] = u
+			comps.all[u.id].connections[node.id] = node
+		}
+	}
+	for i := 0; i < len(comps.edges); {
+		if comps.edges[i].from == v.id {
+			comps.edges[i].from = u.id
+		}
+		if comps.edges[i].to == v.id {
+			comps.edges[i].to = u.id
+		}
+		if comps.edges[i].from == comps.edges[i].to {
+			comps.edges = append(comps.edges[:i], comps.edges[i+1:]...)
+			continue
+		}
+		i++
+	}
+}
+
+func cutInGroups(comps *components, edges []connections) int {
+	var final1, final2 string
+	for i, edge := range edges {
+		cut1 := edge.track[0]
+		cut2 := edge.track[1]
+		delete(comps.all[cut1].conns, cut2)
+		delete(comps.all[cut2].conns, cut1)
+		if i == len(edges)-1 {
+			final1 = cut1
+			final2 = cut2
+		}
+	}
+	group1 := countN(comps, final1)
+	group2 := countN(comps, final2)
+	return group1 * group2
+}
+
+func countN(comps *components, start string) int {
+	visited := make(map[string]bool)
+	counter := 0
+	entry := start
+	path := []string{entry}
+	for len(path) > 0 {
+		currentPath := path[0]
+		path = path[1:]
+		if _, ok := visited[currentPath]; ok {
+			continue
+		}
+		counter++
+		currentcomponent := comps.all[currentPath]
+		visited[currentPath] = true
+		for key := range currentcomponent.conns {
+			if _, ok := visited[key]; ok {
+				continue
+			}
+			path = append(path, key)
+		}
+	}
+	return counter
 }
diff --git a/2023/day25/testinput b/2023/day25/testinput
new file mode 100644
index 0000000..bbfda0b
--- /dev/null
+++ b/2023/day25/testinput
@@ -0,0 +1,13 @@
+jqt: rhn xhk nvd
+rsh: frs pzl lsr
+xhk: hfx
+cmg: qnr nvd lhk bvb
+rhn: xhk bvb hfx
+bvb: xhk hfx
+pzl: lsr hfx nvd
+qnr: nvd
+ntq: jqt hfx bvb xhk
+nvd: lhk
+lsr: lhk
+rzs: qnr cmg lsr rsh
+frs: qnr lhk lsr
diff --git a/helpers/queue.go b/helpers/queue.go
index 0b12f27..715dbfa 100644
--- a/helpers/queue.go
+++ b/helpers/queue.go
@@ -1,5 +1,7 @@
 package aoc
 
+import "fmt"
+
 type Queue[T any] struct {
 	items []T
 }
@@ -80,3 +82,11 @@ func (q *Queue[T]) Insert(item T, location int) {
 func (q *Queue[T]) InsertVector(items []T, location int) {
 	q.items = append(q.items[:location], append(items, q.items[location:]...)...)
 }
+
+func (q Queue[T]) String() string {
+	res := "[ "
+	for i := range q.items {
+		res = fmt.Sprintf("%s %v", res, q.items[i])
+	}
+	return fmt.Sprintf("%s ]", res)
+}