re-organise repo

2022/go/day07/day07.go

@@ -0,0 +1,112 @@
+package day07
+
+import (
+	"strings"
+
+	"adventofcode2022/utils"
+)
+
+type dir struct {
+	name   string
+	files  map[string]int
+	subdir map[string]*dir
+	parent *dir
+	size   int
+}
+
+func Part1(input string) int {
+	root := dir{name: "/", files: map[string]int{}, subdir: map[string]*dir{}, parent: nil}
+	root.parse(input)
+	sum := 0
+	find_dirs_part1(&root, 100000, &sum)
+	return sum
+}
+
+func Part2(input string) int {
+	root := dir{name: "/", files: map[string]int{}, subdir: map[string]*dir{}, parent: nil}
+	root.parse(input)
+	unused := 70000000 - root.size
+	need := 30000000 - unused
+	dir_size := 0
+	find_dirs_part2(&root, need, &dir_size)
+	return dir_size
+}
+
+func find_dirs_part1(d *dir, size int, sum *int) {
+	// recurse into subdir
+	for _, subdir := range d.subdir {
+		if (subdir.size) <= size {
+			*sum += subdir.size
+		}
+		find_dirs_part1(subdir, size, sum)
+	}
+}
+
+func find_dirs_part2(d *dir, size int, sum *int) {
+	// recurse into subdir
+	for _, subdir := range d.subdir {
+		if (subdir.size) >= size && (*sum == 0 || (subdir.size) < *sum) {
+			*sum = subdir.size
+		}
+		find_dirs_part2(subdir, size, sum)
+	}
+}
+
+func (root *dir) parse(input string) {
+	c := root
+
+	for _, line := range strings.Split(input, "\n") {
+		pieces := strings.Split(line, " ")
+		if pieces[0] == "$" {
+			if pieces[1] == "cd" {
+				if pieces[2] == ".." {
+					c = c.parent
+				} else if pieces[2] == "/" {
+					c = root
+				} else {
+					c = c.addDirectoryIfMissing(pieces[2])
+				}
+			} else if pieces[1] == "ls" {
+				// no need to do anything
+			} else {
+				panic("oops")
+			}
+		} else if pieces[0] == "dir" {
+			c.addDirectoryIfMissing(pieces[1])
+		} else {
+			c.addFileIfMissing(pieces[1], utils.MustAtoi(pieces[0]))
+		}
+	}
+}
+
+func (d *dir) addDirectoryIfMissing(name string) *dir {
+	t, ok := d.subdir[name]
+	if !ok {
+		t = &dir{
+			name:   name,
+			files:  map[string]int{},
+			subdir: map[string]*dir{},
+			parent: d,
+		}
+		d.subdir[name] = t
+	}
+	return t
+}
+
+func (d *dir) addFileIfMissing(name string, size int) {
+	t, ok := d.files[name]
+	if ok {
+		if t != size {
+			panic("oops")
+		}
+	} else {
+		current := d
+		d.files[name] = size
+		
+		for current.name != "/" {
+			current.size += size
+			current = current.parent
+		}
+		current.size += size
+	}
+}

2022/go/day07/day07_test.go

@@ -0,0 +1,63 @@
+package day07
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestPart1(t *testing.T) {
+	r := Part1(
+`$ cd /
+$ ls
+dir a
+14848514 b.txt
+8504156 c.dat
+dir d
+$ cd a
+$ ls
+dir e
+29116 f
+2557 g
+62596 h.lst
+$ cd e
+$ ls
+584 i
+$ cd ..
+$ cd ..
+$ cd d
+$ ls
+4060174 j
+8033020 d.log
+5626152 d.ext
+7214296 k`)
+	require.Equal(t, 95437, r)
+}
+
+func TestPart2(t *testing.T) {
+	r := Part2(
+`$ cd /
+$ ls
+dir a
+14848514 b.txt
+8504156 c.dat
+dir d
+$ cd a
+$ ls
+dir e
+29116 f
+2557 g
+62596 h.lst
+$ cd e
+$ ls
+584 i
+$ cd ..
+$ cd ..
+$ cd d
+$ ls
+4060174 j
+8033020 d.log
+5626152 d.ext
+7214296 k`)
+	require.Equal(t, 24933642, r)
+}