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-rw-r--r--2021/09/example5
-rw-r--r--2021/09/first.go69
-rw-r--r--2021/09/first_v2.go64
-rw-r--r--2021/09/input100
-rw-r--r--2021/09/second.go85
5 files changed, 323 insertions, 0 deletions
diff --git a/2021/09/example b/2021/09/example
new file mode 100644
index 0000000..6dee4a4
--- /dev/null
+++ b/2021/09/example
@@ -0,0 +1,5 @@
+2199943210
+3987894921
+9856789892
+8767896789
+9899965678
diff --git a/2021/09/first.go b/2021/09/first.go
new file mode 100644
index 0000000..edfca87
--- /dev/null
+++ b/2021/09/first.go
@@ -0,0 +1,69 @@
+package main
+
+import (
+ "bufio"
+ "fmt"
+ "os"
+)
+
+// DOES NOT WORK!!!
+
+func countMins(prev []byte, prevS []bool) (score int) {
+ for i, v := range prevS {
+ if v {
+ fmt.Println(prev[i])
+ score += int(prev[i]) + 1
+ }
+ }
+ return
+}
+
+func main() {
+ score := 0
+
+ s := bufio.NewScanner(os.Stdin)
+ s.Scan()
+ width := len(s.Text())
+ prevS := make([]bool, width)
+ prev := make([]byte, width)
+ for i, ch := range s.Text() {
+ prev[i] = byte(ch) - '0'
+ if i == 0 {
+ prevS[i] = true
+ } else if prev[i] < prev[i-1] {
+ prevS[i-1] = false
+ prevS[i] = true
+ }
+ }
+
+ curS := make([]bool, width)
+ cur := make([]byte, width)
+ fmt.Println(s.Text())
+ for s.Scan() {
+ for i, ch := range s.Text() {
+ cur[i] = byte(ch) - '0'
+ if i > 0 && cur[i] < cur[i-1] {
+ curS[i-1] = false
+ if cur[i] < prev[i] {
+ prevS[i] = false
+ curS[i] = true
+ } else {
+ curS[i] = false
+ }
+ } else {
+ if cur[i] < prev[i] {
+ prevS[i] = false
+ }
+ curS[i] = false
+ }
+ }
+ fmt.Printf("%+v\n", prevS)
+ fmt.Println(s.Text())
+ score += countMins(prev, prevS)
+ copy(prev, cur)
+ copy(prevS, curS)
+ }
+ score += countMins(prev, prevS)
+ fmt.Printf("%+v\n", prevS)
+ fmt.Println(score)
+}
diff --git a/2021/09/first_v2.go b/2021/09/first_v2.go
new file mode 100644
index 0000000..0c11bcd
--- /dev/null
+++ b/2021/09/first_v2.go
@@ -0,0 +1,64 @@
+package main
+
+import (
+ "bufio"
+ "fmt"
+ "os"
+)
+
+var (
+ grid [][]byte = make([][]byte, 0)
+ width, height int
+)
+
+func isMin(x, y int) bool {
+ var left, right, top, bottom byte
+ if x == 0 {
+ left = '9'
+ } else {
+ left = grid[x-1][y]
+ }
+ if x == height-1 {
+ right = '9'
+ } else {
+ right = grid[x+1][y]
+ }
+ if y == 0 {
+ top = '9'
+ } else {
+ top = grid[x][y-1]
+ }
+ if y == width-1 {
+ bottom = '9'
+ } else {
+ bottom = grid[x][y+1]
+ }
+ return grid[x][y] < top && grid[x][y] < bottom && grid[x][y] < left && grid[x][y] < right
+}
+
+func main() {
+ s := bufio.NewScanner(os.Stdin)
+ s.Scan()
+ width = len(s.Text())
+ for {
+ line := make([]byte, width)
+ for i, ch := range s.Text() {
+ line[i] = byte(ch)
+ }
+ grid = append(grid, line)
+ if !s.Scan() {
+ break
+ }
+ }
+ height = len(grid)
+
+ score := 0
+ for y := 0; y < width; y++ {
+ for x := 0; x < height; x++ {
+ if isMin(x, y) {
+ score += int(grid[x][y]-'0') + 1
+ }
+ }
+ }
+ fmt.Println(score)
+}
diff --git a/2021/09/input b/2021/09/input
new file mode 100644
index 0000000..c299a49
--- /dev/null
+++ b/2021/09/input
@@ -0,0 +1,100 @@
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diff --git a/2021/09/second.go b/2021/09/second.go
new file mode 100644
index 0000000..6cba3dd
--- /dev/null
+++ b/2021/09/second.go
@@ -0,0 +1,85 @@
+package main
+
+import (
+ "bufio"
+ "fmt"
+ "os"
+ "sort"
+)
+
+var (
+ grid [][]byte = make([][]byte, 0)
+ width, height int
+)
+
+func isMin(x, y int) bool {
+ var left, right, top, bottom byte
+ if x == 0 {
+ left = '9'
+ } else {
+ left = grid[x-1][y]
+ }
+ if x == height-1 {
+ right = '9'
+ } else {
+ right = grid[x+1][y]
+ }
+ if y == 0 {
+ top = '9'
+ } else {
+ top = grid[x][y-1]
+ }
+ if y == width-1 {
+ bottom = '9'
+ } else {
+ bottom = grid[x][y+1]
+ }
+ return grid[x][y] < top && grid[x][y] < bottom && grid[x][y] < left && grid[x][y] < right
+}
+
+type Min struct {
+ x, y int
+}
+
+var minimums []Min
+
+func main() {
+ s := bufio.NewScanner(os.Stdin)
+ s.Scan()
+ width = len(s.Text())
+ for {
+ line := make([]byte, width)
+ for i, ch := range s.Text() {
+ line[i] = byte(ch)
+ }
+ grid = append(grid, line)
+ if !s.Scan() {
+ break
+ }
+ }
+ height = len(grid)
+
+ for y := 0; y < width; y++ {
+ for x := 0; x < height; x++ {
+ if isMin(x, y) {
+ minimums = append(minimums, Min{x, y})
+ }
+ }
+ }
+
+ basins := make([]int, 0)
+ for _, m := range minimums {
+ basins = append(basins, computeBasinSize(m.x, m.y))
+ }
+ sort.Ints(basins)
+ basins = basins[len(basins)-3:]
+ fmt.Println(basins[0] * basins[1] * basins[2])
+}
+
+func computeBasinSize(x, y int) int {
+ if x < 0 || x >= height || y < 0 || y >= width || grid[x][y] == '9' {
+ return 0
+ }
+ grid[x][y] = '9'
+ return 1 + computeBasinSize(x-1, y) + computeBasinSize(x+1, y) + computeBasinSize(x, y-1) + computeBasinSize(x, y+1)
+}