Day 12

README.md

@@ -14,7 +14,7 @@ A small practice project created to get familiar with Go syntax.
 - [x] day 9
 - [x] day 10 
 - [x] day 11
-- [ ] day 12
+- [x] day 12
 - [ ] day 13
 - [ ] day 14
 - [ ] day 15

day12/day12.go

@@ -11,17 +11,41 @@ import (
 )
 
 type Row struct {
-	rawSeq        []string
-	damagedGroups []int
+	seq       []string
+	dmgGroups []int
 }
 
+var calcCache = make(map[string]int)
+
 func Solution1(filepath string) int {
 	rows := parseInput(filepath)
 
 	result := 0
 	for _, r := range rows {
-		result += countCombs(r.rawSeq, r.damagedGroups)
+		result += countCombs(r.seq, r.dmgGroups)
+	}
+	return result
+}
+
+func Solution2(filepath string) int {
+	rows := parseInput(filepath)
+
+	result := 0
+	for _, r := range rows {
+		// x5 unfold
+		newSeq := make([]string, 0, len(r.seq)*5+4)
+		newDmgGroups := make([]int, 0, len(r.dmgGroups)*5)
+		for i := 0; i < 5; i++ {
+			newSeq = append(newSeq, r.seq...)
+			if i < 4 {
+				newSeq = append(newSeq, "?")
+			}
+			newDmgGroups = append(newDmgGroups, r.dmgGroups...)
+		}
+
+		result += countCombs(newSeq, newDmgGroups)
 	}
+
 	return result
 }
 
@@ -45,6 +69,12 @@ func countCombs(s []string, g []int) int {
 		}
 	}
 
+	// try cache
+	key := cacheKey(s, g)
+	if cachedRes, ok := calcCache[key]; ok {
+		return cachedRes
+	}
+
 	// ? eq . or # branching:
 	// ? eq .
 	result := 0
@@ -70,11 +100,12 @@ func countCombs(s []string, g []int) int {
 
 	}
 
+	calcCache[key] = result
 	return result
 }
 
-func Solution2(filepath string) int {
-	return -1
+func cacheKey(s []string, n []int) string {
+	return fmt.Sprintf("%v;%v", s, n)
 }
 
 func parseInput(filepath string) []Row {
@@ -89,7 +120,7 @@ func parseInput(filepath string) []Row {
 		divInput := strings.Split(scanner.Text(), " ")
 		seq := strings.Split(divInput[0], "")
 		dmgGroups := strings.Split(divInput[1], ",")
-		m = append(m, Row{rawSeq: seq, damagedGroups: parseInts(dmgGroups)})
+		m = append(m, Row{seq: seq, dmgGroups: parseInts(dmgGroups)})
 	}
 	if err = scanner.Err(); err != nil {
 		log.Fatalf("Error during input file read: %v\n", err.Error())
@@ -98,14 +129,6 @@ func parseInput(filepath string) []Row {
 	return m
 }
 
-func printRows(rows []Row) {
-	fmt.Println("-----MATRIX START-----")
-	for i, row := range rows {
-		fmt.Printf("Row %d: %v | %v\n", i, strings.Join(row.rawSeq, ""), row.damagedGroups)
-	}
-	fmt.Println("------MATRIX END-----")
-}
-
 func parseInts(sNums []string) []int {
 	var nums []int
 	for _, sNum := range sNums {

day12/day12_test.go

@@ -22,3 +22,19 @@ func TestSolutio1(t *testing.T) {
 		}
 	}
 }
+
+func TestSolutio2(t *testing.T) {
+	cases := map[string]int{
+		"test_input11": 525152,
+	}
+
+	for input, expectedResult := range cases {
+		result := Solution2(input)
+
+		if result == expectedResult {
+			fmt.Printf("Solution2()=%d, OK\n", result)
+		} else {
+			t.Fatalf("Solution2()=%d, expecting %d, FAIL\n", result, expectedResult)
+		}
+	}
+}