day23p2

day23p2/solution.go

@@ -0,0 +1,74 @@
+package day23p2
+
+import (
+	"io"
+	"sort"
+	"strings"
+
+	"aoc/utils"
+)
+
+type Party map[string]bool
+
+func Solve(r io.Reader) any {
+	lines := utils.ReadLines(r)
+
+	network := make(map[string]map[string]bool)
+
+	for _, line := range lines {
+		parts := strings.Split(line, "-")
+		a, b := parts[0], parts[1]
+		if _, ok := network[a]; !ok {
+			network[a] = make(map[string]bool)
+		}
+		network[a][b] = true
+		if _, ok := network[b]; !ok {
+			network[b] = make(map[string]bool)
+		}
+		network[b][a] = true
+	}
+
+	var largestParty Party
+
+	for c1 := range network {
+		party := dfs(network, c1, make(Party))
+		if len(party) > len(largestParty) {
+			largestParty = party
+		}
+	}
+	largestPartyPW := make([]string, 0, len(largestParty))
+	for k := range largestParty {
+		largestPartyPW = append(largestPartyPW, k)
+	}
+	sort.Strings(largestPartyPW)
+
+	return strings.Join(largestPartyPW, ",")
+}
+
+func dfs(network map[string]map[string]bool, c string, visited Party) Party {
+	visited[c] = true
+	var largestParty Party
+NextParty:
+	for c2 := range network[c] {
+		if visited[c2] {
+			continue
+		}
+		for prev := range visited {
+			if !network[c2][prev] {
+				continue NextParty
+			}
+		}
+		party := dfs(network, c2, visited)
+		if len(party) > len(largestParty) {
+			largestParty = party
+		}
+	}
+	if len(largestParty) == 0 {
+		// deep clone visited
+		largestParty = make(Party)
+		for k, v := range visited {
+			largestParty[k] = v
+		}
+	}
+	return visited
+}

day23p2/solution_test.go

@@ -0,0 +1,64 @@
+package day23p2
+
+import (
+	"strings"
+	"testing"
+
+	"aoc/utils"
+)
+
+var testInput = `kh-tc
+qp-kh
+de-cg
+ka-co
+yn-aq
+qp-ub
+cg-tb
+vc-aq
+tb-ka
+wh-tc
+yn-cg
+kh-ub
+ta-co
+de-co
+tc-td
+tb-wq
+wh-td
+ta-ka
+td-qp
+aq-cg
+wq-ub
+ub-vc
+de-ta
+wq-aq
+wq-vc
+wh-yn
+ka-de
+kh-ta
+co-tc
+wh-qp
+tb-vc
+td-yn`
+
+func TestSolve(t *testing.T) {
+	tests := []struct {
+		input  string
+		answer string
+	}{
+		{testInput, "co,de,ka,ta"},
+	}
+
+	if testing.Verbose() {
+		utils.Verbose = true
+	}
+
+	for _, test := range tests {
+		r := strings.NewReader(test.input)
+
+		result := Solve(r).(string)
+
+		if result != test.answer {
+			t.Errorf("Expected %s, got %s", test.answer, result)
+		}
+	}
+}