Day313

README.md

@@ -320,6 +320,7 @@ problems from
 * [Day 310](https://github.com/vaskoz/dailycodingproblem-go/issues/633)
 * [Day 311](https://github.com/vaskoz/dailycodingproblem-go/issues/635)
 * [Day 312](https://github.com/vaskoz/dailycodingproblem-go/issues/637)
+* [Day 313](https://github.com/vaskoz/dailycodingproblem-go/issues/639)
 * [Day 314](https://github.com/vaskoz/dailycodingproblem-go/issues/640)
 * [Day 315](https://github.com/vaskoz/dailycodingproblem-go/issues/642)
 * [Day 317](https://github.com/vaskoz/dailycodingproblem-go/issues/645)

day313/problem.go

@@ -0,0 +1,89 @@
+package day313
+
+// MovesToUnlock returns the minimum number of moves to unlock a rotary
+// lock avoid all dead ends.
+// Returns -1 if it's not possible.
+// Panics if the input data is inconsistent.
+// Runs in O(N) or O(V+E) time since BFS is a linear algorithm.
+func MovesToUnlock(start, target [3]int, deadEnds [][3]int) int {
+	if start == target {
+		return 0
+	}
+
+	for _, v := range start {
+		if v < 0 || v > 9 {
+			panic("start values must all be 0-9")
+		}
+	}
+
+	for _, v := range target {
+		if v < 0 || v > 9 {
+			panic("target values must all be 0-9")
+		}
+	}
+
+	graph := make([][][]int, 10)
+	for i := range graph {
+		graph[i] = make([][]int, 10)
+		for j := range graph[i] {
+			graph[i][j] = make([]int, 10)
+		}
+	}
+
+	for _, de := range deadEnds {
+		for _, v := range de {
+			if v < 0 || v > 9 {
+				panic("dead end values must all be 0-9")
+			}
+		}
+
+		x, y, z := de[0], de[1], de[2]
+		graph[x][y][z] = -1
+	}
+
+	bfs(graph, start)
+
+	return graph[target[0]][target[1]][target[2]] - 1
+}
+
+func bfs(g [][][]int, start [3]int) {
+	var q [][3]int
+
+	g[start[0]][start[1]][start[2]] = 1
+
+	q = append(q, start)
+
+	for len(q) != 0 {
+		var v [3]int
+		v, q = q[0], q[1:]
+		dist := g[v[0]][v[1]][v[2]]
+
+		for _, dir := range [][3]int{
+			{-1, 0, 0}, {0, -1, 0}, {0, 0, -1},
+			{1, 0, 0}, {0, 1, 0}, {0, 0, 1},
+		} {
+			next := coord(v, dir)
+			x, y, z := next[0], next[1], next[2]
+
+			if g[x][y][z] == 0 {
+				g[x][y][z] = dist + 1
+
+				q = append(q, next)
+			}
+		}
+	}
+}
+
+func coord(start, direction [3]int) [3]int {
+	var result [3]int
+	for i := range result {
+		result[i] = start[i] + direction[i]
+		if result[i] > 9 {
+			result[i] = 0
+		} else if result[i] < 0 {
+			result[i] = 9
+		}
+	}
+
+	return result
+}

day313/problem_test.go

@@ -0,0 +1,89 @@
+package day313
+
+import "testing"
+
+// nolint
+var testcases = []struct {
+	start, target [3]int
+	deadEnds      [][3]int
+	expected      int
+}{
+	{
+		[3]int{0, 0, 0},
+		[3]int{7, 1, 9},
+		[][3]int{{1, 1, 1}},
+		5,
+	},
+	{
+		[3]int{0, 0, 0},
+		[3]int{0, 0, 0},
+		[][3]int{{1, 1, 1}},
+		0,
+	},
+	{
+		[3]int{0, 0, 0},
+		[3]int{5, 5, 5},
+		[][3]int{{1, 0, 0}, {0, 1, 0}, {9, 0, 0}, {0, 9, 0}, {0, 0, 1}, {0, 0, 9}},
+		-1,
+	},
+	{
+		[3]int{0, 0, 0},
+		[3]int{5, 5, 5},
+		[][3]int{{0, 1, 0}, {9, 0, 0}, {0, 9, 0}, {0, 0, 1}, {0, 0, 9}},
+		15,
+	},
+}
+
+func TestMovesToUnlock(t *testing.T) {
+	t.Parallel()
+
+	for _, tc := range testcases {
+		if result := MovesToUnlock(tc.start, tc.target, tc.deadEnds); result != tc.expected {
+			t.Errorf("Expected %v, got %v", tc.expected, result)
+		}
+	}
+}
+
+func TestMovesToUnlockBadStartPanic(t *testing.T) {
+	t.Parallel()
+
+	defer func() {
+		if err := recover(); err == nil {
+			t.Errorf("Expected a panic for bad start coordinates")
+		}
+	}()
+
+	MovesToUnlock([3]int{-1, 10, 5}, [3]int{1, 1, 1}, [][3]int{})
+}
+
+func TestMovesToUnlockBadTargetPanic(t *testing.T) {
+	t.Parallel()
+
+	defer func() {
+		if err := recover(); err == nil {
+			t.Errorf("Expected a panic for bad target coordinates")
+		}
+	}()
+
+	MovesToUnlock([3]int{0, 0, 0}, [3]int{10, 1, 1}, [][3]int{})
+}
+
+func TestMovesToUnlockBadDeadEndPanic(t *testing.T) {
+	t.Parallel()
+
+	defer func() {
+		if err := recover(); err == nil {
+			t.Errorf("Expected a panic for bad dead end coordinates")
+		}
+	}()
+
+	MovesToUnlock([3]int{0, 0, 0}, [3]int{1, 1, 1}, [][3]int{{-1, 0, 0}})
+}
+
+func BenchmarkMovesToUnlock(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		for _, tc := range testcases {
+			MovesToUnlock(tc.start, tc.target, tc.deadEnds)
+		}
+	}
+}

day333/problem.go

@@ -5,6 +5,8 @@ package day333
 // NOTE: This is not bidirectional.
 type Knowing map[int]map[int]bool
 
+// Knows is a O(1) method that answers if 'a' "knows" 'b'.
+// This does not imply that 'b' "knows" 'a'.
 func (k *Knowing) Knows(a, b int) bool {
 	if known, exists := (*k)[a]; exists {
 		return known[b]