chore: save hacker rank

README.md.sig

@@ -0,0 +1,6 @@
+-----BEGIN SSH SIGNATURE-----
+U1NIU0lHAAAAAQAAADMAAAALc3NoLWVkMjU1MTkAAAAgZ+OuJYdd3UiUbyBuO1RlsQR20a
+Qm5mKneuMxRjGo3zkAAAAEZmlsZQAAAAAAAAAGc2hhNTEyAAAAUwAAAAtzc2gtZWQyNTUx
+OQAAAED8T4C6WILXYZ1KxqDIlVhlrAEjr1Vc+tn8ypcVM3bN7iOexVvuUuvm90nr8eEwKU
+acrdDxmq2S+oysQbK+pMUE
+-----END SSH SIGNATURE-----

aoc_test.go

@@ -9,66 +9,6 @@ import (
 	aoc "go.sour.is/advent-of-code"
 )
 
-func TestReverse(t *testing.T) {
-	is := is.New(t)
-
-	is.Equal(aoc.Reverse([]int{1, 2, 3, 4}), []int{4, 3, 2, 1})
-}
-
-func TestLCM(t *testing.T) {
-	is := is.New(t)
-
-	is.Equal(aoc.LCM([]int{}...), 0)
-	is.Equal(aoc.LCM(5), 5)
-	is.Equal(aoc.LCM(5, 3), 15)
-	is.Equal(aoc.LCM(5, 3, 2), 30)
-}
-
-func TestReadStringToInts(t *testing.T) {
-	is := is.New(t)
-
-	is.Equal(aoc.ReadStringToInts([]string{"1", "2", "3"}), []int{1, 2, 3})
-}
-
-func TestRepeat(t *testing.T) {
-	is := is.New(t)
-
-	is.Equal(aoc.Repeat(5, 3), []int{5, 5, 5})
-}
-
-func TestPower2(t *testing.T) {
-	is := is.New(t)
-
-	is.Equal(aoc.Power2(0), 1)
-	is.Equal(aoc.Power2(1), 2)
-	is.Equal(aoc.Power2(2), 4)
-}
-
-func TestABS(t *testing.T) {
-	is := is.New(t)
-
-	is.Equal(aoc.ABS(1), 1)
-	is.Equal(aoc.ABS(0), 0)
-	is.Equal(aoc.ABS(-1), 1)
-}
-
-func TestTranspose(t *testing.T) {
-	is := is.New(t)
-
-	is.Equal(
-		aoc.Transpose(
-			[][]int{
-				{1, 1},
-				{0, 0},
-				{1, 1},
-			},
-		),
-		[][]int{
-			{1, 0, 1},
-			{1, 0, 1},
-		},
-	)
-}
 
 func TestList(t *testing.T) {
 	is := is.New(t)
@@ -116,23 +56,6 @@ func TestPriorityQueue(t *testing.T) {
 	is.True(v == nil)
 }
 
-func TestSet(t *testing.T) {
-	is := is.New(t)
-
-	s := aoc.Set(1, 2, 3)
-	is.True(!s.Has(0))
-	is.True(s.Has(1))
-	is.True(s.Has(2))
-	is.True(s.Has(3))
-	is.True(!s.Has(4))
-
-	s.Add(4)
-	is.True(s.Has(4))
-
-	items := s.Items()
-	sort.Ints(items)
-	is.Equal(items, []int{1, 2, 3, 4})
-}
 
 func ExamplePriorityQueue() {
 	type memo struct {
@@ -194,26 +117,6 @@ func ExamplePriorityQueue() {
 	// point 5 is 22 steps away.
 	// point 6 is 19 steps away.
 }
-
-func TestStack(t *testing.T) {
-	is := is.New(t)
-
-	s := aoc.Stack(1, 2, 3, 4)
-	is.True(!s.IsEmpty())
-	is.Equal(s.Pop(), 4)
-	is.Equal(s.Pop(), 3)
-	is.Equal(s.Pop(), 2)
-	is.Equal(s.Pop(), 1)
-	is.True(s.IsEmpty())
-	s.Push(4, 3, 2, 1)
-	is.True(!s.IsEmpty())
-	is.Equal(s.Pop(), 1)
-	is.Equal(s.Pop(), 2)
-	is.Equal(s.Pop(), 3)
-	is.Equal(s.Pop(), 4)
-	is.True(s.IsEmpty())
-}
-
 func TestGraph(t *testing.T) {
 	is := is.New(t)
 

go.mod

@@ -1,8 +1,6 @@
 module go.sour.is/advent-of-code
 
-go 1.21.4
+go 1.22.0
-
-toolchain go1.21.5
 
 require (
 	github.com/matryer/is v1.4.1

grids.go

@@ -2,7 +2,11 @@ package aoc
 
 import (
 	"cmp"
+	"fmt"
 	"sort"
+	"strings"
+
+	"golang.org/x/exp/maps"
 )
 
 type Vector struct {
@@ -82,6 +86,76 @@ func (m *Map[I, T]) Valid(p Point[I]) bool {
 	return p[0] >= 0 && p[0] < rows && p[1] >= 0 && p[1] < cols
 }
 
+type cmap[C number, N comparable] struct {
+	base      pather[C, N]
+	neighbors map[N]map[N]C
+}
+
+func (m *cmap[C, N]) Cost(a, b N) C {
+	if v, ok := m.neighbors[a]; ok {
+		return v[b]
+	}
+	return 0
+}
+func (m *cmap[C, N]) Neighbors(n N) []N {
+	if v, ok := m.neighbors[n]; ok {
+		return maps.Keys(v)
+	}
+	return nil
+}
+func (m *cmap[C, N]) Target(n N, c C) bool {
+	return m.base.Target(n, c)
+}
+func (m *cmap[C, N]) String() string {
+	var b = &strings.Builder{}
+
+	for k, nbs := range m.neighbors {
+		fmt.Fprintln(b, k)
+		for to, c := range nbs {
+			fmt.Fprintln(b, "  ", to, c)
+		}
+	}
+
+	return b.String()
+}
+
+func CompressMap[C number, N comparable](p pather[C, N], start N) pather[C, N] {
+	var next = []N{start}
+	var visited = make(map[N]map[N]C)
+
+	var n N
+	for len(next) > 0 {
+		n, next = next[len(next)-1], next[:len(next)-1]
+
+		if _, ok := visited[n]; ok {
+			continue
+		}
+
+		nbs := p.Neighbors(n)
+		if len(nbs) == 2 {
+			a, b := nbs[0], nbs[1]
+			if to, ok := visited[a]; ok {
+				to[b] = to[n] + p.Cost(n, b)
+				delete(to, n)
+				visited[a] = to
+			} else if to, ok := visited[b]; ok {
+				to[a] = to[n] + p.Cost(n, a)
+				delete(to, n)
+				visited[b] = to
+			}
+			continue
+		}
+
+		visited[n] = make(map[N]C)
+		next = append(next, nbs...)
+		for _, to := range nbs {
+			visited[n][to] = p.Cost(n, to)
+		}
+	}
+
+	return &cmap[C, N]{base: p, neighbors: visited}
+}
+
 type adjacencyList[V any, C comparable] map[C][]V
 type graph[V any, W cmp.Ordered, C comparable] map[C]*vertex[V, W]
 type graphOption[V any, W cmp.Ordered, C comparable] func(g *graph[V, W, C])
@@ -117,7 +191,7 @@ func Graph[V any, W cmp.Ordered, C comparable](opts ...graphOption[V, W, C]) *gr
 	return &g
 }
 func (g *graph[V, W, C]) AddVertex(id C, value V) {
-	(*g)[id] = &vertex[V,W]{Value: value}
+	(*g)[id] = &vertex[V, W]{Value: value}
 }
 func (g *graph[V, W, C]) AddEdge(from, to C, w W) {
 	if g == nil {
@@ -130,7 +204,7 @@ func (g *graph[V, W, C]) AddEdge(from, to C, w W) {
 		return
 	}
 
-	(*g)[from].Edges = append((*g)[from].Edges, edge[V,W]{(*g)[to], w})
+	(*g)[from].Edges = append((*g)[from].Edges, edge[V, W]{(*g)[to], w})
 }
 func (g *graph[V, W, C]) Neighbors(v C) []V {
 	if g == nil {
@@ -170,5 +244,3 @@ func WithAdjacencyList[W cmp.Ordered, C comparable](list adjacencyList[C, C]) gr
 		}
 	}
 }
-
-// func GraphFromMap()

hacker01/hacker.go

@@ -0,0 +1,69 @@
+package main
+
+import "fmt"
+import "os"
+import "bufio"
+import "strconv"
+import "strings"
+
+
+var input1 = strings.NewReader(`
+6
+1 2 5 3 6 4
+`)
+
+var input2 = strings.NewReader(`
+15
+1 14 3 7 4 5 15 6 13 10 11 2 12 8 9
+`)
+
+var input3 = os.Stdin
+
+func main() {
+	var length int
+    var tree *node
+    
+    scanner := bufio.NewScanner(input1)
+    for scanner.Scan() {
+		if length == 0 {
+			length, _ = strconv.Atoi(scanner.Text())
+			continue
+		}
+
+        for _, txt := range strings.Fields(scanner.Text()) {		
+			if v, err := strconv.Atoi(txt); err == nil {
+                tree = insert(tree, &node{value: v})
+            }
+        }
+    }
+
+    foo(input{1, "hi"})
+    
+    fmt.Println(tree)
+}
+
+type node struct {
+    value int
+    left *node
+    right *node
+}
+
+func insert(root, n *node) *node {
+        if root == nil {
+            return n
+        }
+        if root.value > n.value {
+            root.left = insert(root.left, n)
+            return root
+        }
+        root.right = insert(root.right, n)
+        return root
+}
+
+func (n *node) String() string {
+    if n == nil { return "" }
+    return fmt.Sprintf("%v %v%v", n.value, n.left.String(), n.right.String())
+}
+
+type input struct{a int; b string}
+func foo (in input) {}

hacker02/hacker.go

@@ -0,0 +1,109 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"io"
+	"os"
+	"strconv"
+	"strings"
+
+	aoc "go.sour.is/advent-of-code"
+)
+
+/*
+ * Complete the 'cookies' function below.
+ *
+ * The function is expected to return an INTEGER.
+ * The function accepts following parameters:
+ *  1. INTEGER k
+ *  2. INTEGER_ARRAY A
+ */
+
+func cookies(k int32, A []int32) int32 {
+	var i int32
+	// fmt.Println(" ", A)
+	// sort.Slice(A, func(i, j int) bool { return A[j] < A[i]})
+	// for A[len(A)-1] < k {
+	//     if len(A) < 2 {
+	//         return -1
+	//     }
+	//     // fmt.Println(" ", A[len(A)-1], " + 2x", A[len(A)-2], 2*A[len(A)-2] + A[len(A)-1])
+	//     A[len(A)-2] = 2*A[len(A)-2] + A[len(A)-1]
+	//     A = A[:len(A)-1]
+
+	//     for j:=len(A)-1; j>0 && A[j] > A[j-1]; j-- {
+	//         A[j], A[j-1] = A[j-1], A[j]
+	//     }
+	//     i++
+	//     fmt.Println("A", len(A), i)
+	// }
+
+	pq := aoc.FibHeap(func(a, b *int32) bool { return *a < *b })
+	for i := range A {
+		pq.Insert(&A[i])
+	}
+	for !pq.IsEmpty() && *pq.GetMin() < k {
+		first := *pq.ExtractMin()
+		second := *pq.ExtractMin()
+		third := first + 2*second
+
+		pq.Insert(&third)
+		i++
+	}
+
+	return i
+}
+
+func main() {
+	reader := bufio.NewReaderSize(os.Stdin, 16*1024*1024)
+
+	stdout, err := os.Create("/dev/stderr")
+	checkError(err)
+
+	defer stdout.Close()
+
+	writer := bufio.NewWriterSize(stdout, 16*1024*1024)
+
+	firstMultipleInput := strings.Split(strings.TrimSpace(readLine(reader)), " ")
+
+	nTemp, err := strconv.ParseInt(firstMultipleInput[0], 10, 64)
+	checkError(err)
+	n := int32(nTemp)
+
+	kTemp, err := strconv.ParseInt(firstMultipleInput[1], 10, 64)
+	checkError(err)
+	k := int32(kTemp)
+
+	ATemp := strings.Split(strings.TrimSpace(readLine(reader)), " ")
+
+	var A []int32
+
+	for i := 0; i < int(n); i++ {
+		AItemTemp, err := strconv.ParseInt(ATemp[i], 10, 64)
+		checkError(err)
+		AItem := int32(AItemTemp)
+		A = append(A, AItem)
+	}
+
+	result := cookies(k, A)
+
+	fmt.Fprintf(writer, "%d\n", result)
+
+	writer.Flush()
+}
+
+func readLine(reader *bufio.Reader) string {
+	str, _, err := reader.ReadLine()
+	if err == io.EOF {
+		return ""
+	}
+
+	return strings.TrimRight(string(str), "\r\n")
+}
+
+func checkError(err error) {
+	if err != nil {
+		panic(err)
+	}
+}

hacker02/input.txt

@@ -0,0 +1,2 @@
+1000000 105823341
+10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 10000 1Line truncated

hacker02/other.txt

@@ -0,0 +1,2 @@
+8 90
+13 47 74 12 89 74 18 38

itertools_test.go

@@ -0,0 +1,44 @@
+package aoc_test
+
+import (
+	"testing"
+
+	"github.com/matryer/is"
+	aoc "go.sour.is/advent-of-code"
+)
+
+func TestReverse(t *testing.T) {
+	is := is.New(t)
+
+	is.Equal(aoc.Reverse([]int{1, 2, 3, 4}), []int{4, 3, 2, 1})
+}
+
+func TestReadStringToInts(t *testing.T) {
+	is := is.New(t)
+
+	is.Equal(aoc.ReadStringToInts([]string{"1", "2", "3"}), []int{1, 2, 3})
+}
+
+func TestRepeat(t *testing.T) {
+	is := is.New(t)
+
+	is.Equal(aoc.Repeat(5, 3), []int{5, 5, 5})
+}
+
+func TestTranspose(t *testing.T) {
+	is := is.New(t)
+
+	is.Equal(
+		aoc.Transpose(
+			[][]int{
+				{1, 1},
+				{0, 0},
+				{1, 1},
+			},
+		),
+		[][]int{
+			{1, 0, 1},
+			{1, 0, 1},
+		},
+	)
+}

math_test.go

@@ -0,0 +1,33 @@
+package aoc_test
+
+import (
+	"testing"
+
+	"github.com/matryer/is"
+	aoc "go.sour.is/advent-of-code"
+)
+
+func TestLCM(t *testing.T) {
+	is := is.New(t)
+
+	is.Equal(aoc.LCM([]int{}...), 0)
+	is.Equal(aoc.LCM(5), 5)
+	is.Equal(aoc.LCM(5, 3), 15)
+	is.Equal(aoc.LCM(5, 3, 2), 30)
+}
+
+func TestPower2(t *testing.T) {
+	is := is.New(t)
+
+	is.Equal(aoc.Power2(0), 1)
+	is.Equal(aoc.Power2(1), 2)
+	is.Equal(aoc.Power2(2), 4)
+}
+
+func TestABS(t *testing.T) {
+	is := is.New(t)
+
+	is.Equal(aoc.ABS(1), 1)
+	is.Equal(aoc.ABS(0), 0)
+	is.Equal(aoc.ABS(-1), 1)
+}

ranger/channel.go

@@ -0,0 +1,15 @@
+package main
+
+
+func countChan(n int) <-chan int {
+	ch := make(chan int)
+
+	go func() {
+		for i := range n {
+			ch <- i
+		}
+		close(ch)
+	}()
+
+	return ch
+}

ranger/range.go

@@ -0,0 +1,84 @@
+package main
+
+// export GOEXPERIMENT=rangefunc
+import "iter"
+
+func Step(start, stop, step int) iter.Seq[int] {
+	if step < 0 {
+		return func(yield func(int) bool) {
+			for i := start; i <= start && i > stop; i += step {
+				next := yield(i)
+				if !next {
+					return
+				}
+			}
+		}
+	}
+
+	if step > 0 {
+		return func(yield func(int) bool) {
+			for i := start; i >= start && i < stop; i += step {
+				next := yield(i)
+				if !next {
+					println("stopped!")
+					return
+				}
+			}
+		}
+	}
+
+	return func(yield func(int) bool) { yield(start) }
+}
+
+func Fib() iter.Seq[uint] {
+	return func(yield func(uint) bool) {
+		previous, value := uint(1), uint(1)
+		next := yield(value)
+		for next {
+			next = yield(value)
+			value, previous = value+previous, value
+			if value < previous {
+				return
+			}
+		}
+	}
+}
+
+func Fizzbuzzed[T int | uint](from iter.Seq[T]) iter.Seq2[T, string] {
+	pull, stop := iter.Pull(from)
+	return func(yield func(T, string) bool) {
+		defer stop()
+		for {
+			var fizzbuzz string
+			p, ok := pull()
+			if !ok {
+				return
+			}
+			if p%3 == 0 {
+				fizzbuzz = "fizz"
+			}
+			if p%5 == 0 {
+				fizzbuzz += "buzz"
+			}
+			if !yield(p, fizzbuzz) {
+				return
+			}
+		}
+	}
+}
+
+// func main() {
+// 	for i, v := range Fizzbuzzed(Fib()) {
+// 		println(i, v)
+// 	}
+// }
+
+func countScan(n int) (func() bool, func() int) {
+	pos := -1
+	return func() bool {
+			pos++
+			return pos < n
+		}, func() int {
+			return pos
+		}
+}

ranger/range_test.go

@@ -0,0 +1,193 @@
+package main_test
+
+import (
+	"testing"
+
+	"github.com/matryer/is"
+)
+
+// func BenchmarkChan(b *testing.B) {
+// 	sum := 0
+
+// 	for n := range countChan(b.N) {
+// 		sum += n
+// 	}
+// 	b.StopTimer()
+// 	b.Log(sum)
+// }
+
+// func BenchmarkScan(b *testing.B) {
+// 	sum := 0
+// 	scan, value := countScan(b.N)
+// 	for scan() {
+// 		sum += value()
+// 	}
+// 	b.StopTimer()
+// 	b.Log(sum)
+// }
+
+// func BenchmarkRange(b *testing.B) {
+// 	sum := 0
+// 	for n := range countRF(b.N) {
+// 		sum += n
+// 	}
+// 	b.StopTimer()
+// 	b.Log(sum)
+// }
+
+// func TestRangeS(t *testing.T) {
+// 	for i := range Step(0, 10, 3) {
+// 		t.Log(i)
+// 	}
+
+// 	for i := range Step(10, 0, -3) {
+// 		t.Log(i)
+// 	}
+// }
+
+func TestSelect(t *testing.T) {
+	done1 := make(chan struct{})
+	done2 := make(chan struct{})
+
+	go func() {
+		close(done1)
+		close(done2)
+	}()
+
+	for i, ch := range []chan struct{}{done1, done2} {
+		<-ch
+		println("closed", i)
+	}
+}
+
+func TestGCD(t *testing.T) {
+	is := is.New(t)
+	is.Equal(gcdOfStrings("ABAB", "ABABAB"), "AB")
+	is.Equal(gcdOfStrings("ABAB", "ABABABAB"), "ABAB")
+	is.Equal(gcdOfStrings("ABC", "ABCABC"), "ABC")
+	is.Equal(gcdOfStrings("ABC", "ABCDEF"), "")
+	is.Equal(gcdOfStrings("AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA", "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"), "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA")
+}
+func gcdOfStrings(str1 string, str2 string) string {
+	if len(str1) == 0 {
+		return ""
+	}
+	runes1 := []rune(str1)
+	runes2 := []rune(str2)
+
+	n := max(len(runes1), len(runes2))
+	m := min(len(runes1), len(runes2))
+
+	if len(runes2) == m {
+		runes1, runes2 = runes2, runes1
+	}
+
+	if isRepeating(runes1, runes2) {
+		return string(runes1)
+	}
+
+	for i := n; i > 0; i-- {
+		if runes1[i%len(runes1)] != runes2[i%len(runes2)] {
+			return ""
+		}
+		gcd := runes2[:i]
+		if isRepeating(gcd, runes1) && isRepeating(gcd, runes2) {
+			return string(gcd)
+		}
+	}
+
+	return ""
+}
+func isRepeating(str1, str2 []rune) bool {
+	if len(str1) > len(str2) {
+		return false
+	}
+	if len(str2)%len(str1) != 0 {
+		return false
+	}
+	for i := range str2 {
+		if str1[i%len(str1)] != str2[i] {
+			return false
+		}
+	}
+	return true
+}
+
+func canPlaceFlowers(flowerbed []int, n int) bool {
+	var c int
+
+	for i := 0; i < len(flowerbed); i++ {
+		if (i == 0 || flowerbed[i-1] == 0) &&
+			flowerbed[i] == 0 &&
+			(i == len(flowerbed)-1 || flowerbed[i+1] == 0) {
+			c++
+			flowerbed[i] = 1
+		}
+	}
+
+	return c >= n
+}
+
+func TestFlowers(t *testing.T) {
+	is := is.New(t)
+	is.Equal(canPlaceFlowers([]int{1, 0, 0, 0, 1}, 1), true)
+	is.Equal(canPlaceFlowers([]int{0, 0, 1, 0, 1}, 1), true)
+	is.Equal(canPlaceFlowers([]int{1, 0, 1, 0, 0}, 1), true)
+}
+
+func dailyTemperatures(temperatures []int) []int {
+	answers := make([]int, len(temperatures))
+	var stack  [][2]int
+	push := func(v int) {
+		if len(stack) == 0 {
+			stack = append(stack, [2]int{v, 1})
+			return
+		}
+		end := len(stack)-1
+		if v < stack[end][0]{
+			stack = append(stack, [2]int{v, 1})
+			return
+
+		}
+		if v == stack[end][0] {
+			stack[len(stack)-1][1]++
+			return
+		}
+
+		var vs = [2]int{v, 1}
+		// for ; end>0; end-- {	
+		// 	if stack[end][0]<vs[0] {
+		// 		vs[1]+=stack[end][1]
+		// 		continue
+		// 	}
+		// 	break
+		// }
+		stack = append(stack, vs)
+	}
+
+	for i := len(temperatures) - 2; i >= 0; i-- {
+		push(temperatures[i+1])
+		currentTemp := temperatures[i]
+		days := 1
+		end := len(stack)-1
+		for j := range stack {
+			nextTemp := stack[end-j]
+			if currentTemp < nextTemp[0] {
+				answers[i] = days
+				break
+			}
+			days+=nextTemp[1]
+		}
+	}
+
+	return answers
+}
+
+func TestTemps(t *testing.T) {
+	is := is.New(t)
+	is.Equal(dailyTemperatures(
+		[]int{73, 74, 75, 71, 69, 72, 76, 73}),
+		[]int{1, 1, 4, 2, 1, 1, 0, 0})
+	is.Equal(dailyTemperatures(
+		[]int{99,99,99,99,100}), []int{4,3,2,1,0})	
+}

ranger/rangefunc.go

@@ -0,0 +1,12 @@
+package main
+
+
+func countRF(n int) func(yield func(int) bool) {
+	return func(yield func(int) bool) {
+		for i := range n {
+			if !yield(i) {
+				return
+			}
+		}
+	}
+} 

search.go

@@ -42,30 +42,6 @@ func (pq *priorityQueue[T]) ExtractMin() *T {
 	return elem
 }
 
-type stack[T any] []T
-
-func Stack[T any](a ...T) *stack[T] {
-	var s stack[T] = a
-	return &s
-}
-func (s *stack[T]) Push(a ...T) {
-	if s == nil {
-		return
-	}
-	*s = append(*s, a...)
-}
-func (s *stack[T]) IsEmpty() bool {
-	return s == nil || len(*s) == 0
-}
-func (s *stack[T]) Pop() T {
-	var a T
-	if s.IsEmpty() {
-		return a
-	}
-	a, *s = (*s)[len(*s)-1], (*s)[:len(*s)-1]
-	return a
-}
-
 // ManhattanDistance the distance between two points measured along axes at right angles.
 func ManhattanDistance[T integer](a, b Point[T]) T {
 	return ABS(a[0]-b[0]) + ABS(a[1]-b[1])

set_test.go

@@ -0,0 +1,27 @@
+package aoc_test
+
+import (
+	"sort"
+	"testing"
+
+	"github.com/matryer/is"
+	aoc "go.sour.is/advent-of-code"
+)
+
+func TestSet(t *testing.T) {
+	is := is.New(t)
+
+	s := aoc.Set(1, 2, 3)
+	is.True(!s.Has(0))
+	is.True(s.Has(1))
+	is.True(s.Has(2))
+	is.True(s.Has(3))
+	is.True(!s.Has(4))
+
+	s.Add(4)
+	is.True(s.Has(4))
+
+	items := s.Items()
+	sort.Ints(items)
+	is.Equal(items, []int{1, 2, 3, 4})
+}