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-rw-r--r--2022/08-treetop-tree-house/example5
-rw-r--r--2022/08-treetop-tree-house/first.zig106
-rw-r--r--2022/08-treetop-tree-house/input99
-rw-r--r--2022/08-treetop-tree-house/second.zig101
4 files changed, 311 insertions, 0 deletions
diff --git a/2022/08-treetop-tree-house/example b/2022/08-treetop-tree-house/example
new file mode 100644
index 0000000..16d6fbd
--- /dev/null
+++ b/2022/08-treetop-tree-house/example
@@ -0,0 +1,5 @@
+30373
+25512
+65332
+33549
+35390
diff --git a/2022/08-treetop-tree-house/first.zig b/2022/08-treetop-tree-house/first.zig
new file mode 100644
index 0000000..07db936
--- /dev/null
+++ b/2022/08-treetop-tree-house/first.zig
@@ -0,0 +1,106 @@
+const std = @import("std");
+
+const example = @embedFile("example");
+const input = @embedFile("input");
+
+pub fn main() anyerror!void {
+ var arena = std.heap.ArenaAllocator.init(std.heap.page_allocator);
+ defer arena.deinit();
+ const allocator = arena.allocator();
+
+ try std.testing.expectEqual(try solve(example, allocator), 21);
+ const result = try solve(input, allocator);
+ try std.io.getStdOut().writer().print("{}\n", .{result});
+}
+
+fn solve(puzzle: []const u8, allocator: std.mem.Allocator) !u64 {
+ var it = std.mem.tokenize(u8, puzzle, "\n");
+ var heights = std.ArrayList(std.ArrayList(u8)).init(allocator);
+ var visibility = std.ArrayList(std.ArrayList(bool)).init(allocator);
+ // process input
+ var line = it.next() orelse unreachable;
+ const width = line.len;
+ while (true) {
+ var h = try heights.addOne();
+ var v = try visibility.addOne();
+ h.* = try std.ArrayList(u8).initCapacity(allocator, width);
+ v.* = try std.ArrayList(bool).initCapacity(allocator, width);
+ try h.*.writer().writeAll(line);
+ v.*.appendAssumeCapacity(true);
+ var i: usize = 1;
+ while (i < width - 1) : (i += 1) {
+ v.*.appendAssumeCapacity(false);
+ }
+ v.*.appendAssumeCapacity(true);
+ if (it.next()) |l| {
+ line = l;
+ } else {
+ break;
+ }
+ }
+ const lastX = width - 1;
+ const lastY = heights.items.len - 1;
+ // init first and last lines edges
+ var x: usize = 1;
+ while (x < width - 1) : (x += 1) {
+ visibility.items[0].items[x] = true;
+ visibility.items[lastY].items[x] = true;
+ }
+ // calculate visible trees in lines
+ var y: usize = 1;
+ while (y < lastY) : (y += 1) {
+ const treeline = heights.items[y];
+ // look right
+ var max = treeline.items[0];
+ x = 1;
+ while (x < lastX) : (x += 1) {
+ if (treeline.items[x] > max) {
+ visibility.items[y].items[x] = true;
+ max = treeline.items[x];
+ }
+ }
+ // look left
+ max = treeline.items[lastX];
+ x = lastX - 1;
+ while (x > 0) : (x -= 1) {
+ if (treeline.items[x] > max) {
+ visibility.items[y].items[x] = true;
+ max = treeline.items[x];
+ }
+ }
+ }
+ // calculate visible trees in columns
+ x = 1;
+ while (x < lastX) : (x += 1) {
+ // look down
+ var max = heights.items[0].items[x];
+ y = 1;
+ while (y < lastY) : (y += 1) {
+ if (heights.items[y].items[x] > max) {
+ visibility.items[y].items[x] = true;
+ max = heights.items[y].items[x];
+ }
+ }
+ // look up
+ max = heights.items[lastY].items[x];
+ y = lastY - 1;
+ while (y > 0) : (y -= 1) {
+ if (heights.items[y].items[x] > max) {
+ visibility.items[y].items[x] = true;
+ max = heights.items[y].items[x];
+ }
+ }
+ }
+ // calculate total
+ var tot: usize = 0;
+ y = 0;
+ while (y <= lastY) : (y += 1) {
+ x = 0;
+ while (x <= lastX) : (x += 1) {
+ if (visibility.items[y].items[x]) {
+ tot += 1;
+ }
+ }
+ }
+ return tot;
+}
diff --git a/2022/08-treetop-tree-house/input b/2022/08-treetop-tree-house/input
new file mode 100644
index 0000000..ffdd5b1
--- /dev/null
+++ b/2022/08-treetop-tree-house/input
@@ -0,0 +1,99 @@
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diff --git a/2022/08-treetop-tree-house/second.zig b/2022/08-treetop-tree-house/second.zig
new file mode 100644
index 0000000..3582143
--- /dev/null
+++ b/2022/08-treetop-tree-house/second.zig
@@ -0,0 +1,101 @@
+const std = @import("std");
+
+const example = @embedFile("example");
+const input = @embedFile("input");
+
+pub fn main() anyerror!void {
+ var arena = std.heap.ArenaAllocator.init(std.heap.page_allocator);
+ defer arena.deinit();
+ const allocator = arena.allocator();
+
+ try std.testing.expectEqual(try solve(example, allocator), 8);
+ const result = try solve(input, allocator);
+ try std.io.getStdOut().writer().print("{}\n", .{result});
+}
+
+fn solve(puzzle: []const u8, allocator: std.mem.Allocator) !u64 {
+ var it = std.mem.tokenize(u8, puzzle, "\n");
+ var heights = std.ArrayList(std.ArrayList(u8)).init(allocator);
+ var scenic = std.ArrayList(std.ArrayList(u64)).init(allocator);
+ // process input
+ var line = it.next() orelse unreachable;
+ const width = line.len;
+ while (true) {
+ var h = try heights.addOne();
+ var v = try scenic.addOne();
+ h.* = try std.ArrayList(u8).initCapacity(allocator, width);
+ v.* = try std.ArrayList(u64).initCapacity(allocator, width);
+ try h.*.writer().writeAll(line);
+ var i: usize = 0;
+ while (i < width) : (i += 1) {
+ v.*.appendAssumeCapacity(0);
+ }
+ if (it.next()) |l| {
+ line = l;
+ } else {
+ break;
+ }
+ }
+ const lastX = width - 1;
+ const lastY = heights.items.len - 1;
+ // init first and last lines edges
+ var x: usize = 1;
+ while (x < width - 1) : (x += 1) {
+ scenic.items[0].items[x] = 0;
+ scenic.items[lastY].items[x] = 0;
+ }
+ // calculate scenic scores tree by tree
+ var tot: usize = 0;
+ var y: usize = 1;
+ while (y < lastY) : (y += 1) {
+ x = 1;
+ while (x < lastX) : (x += 1) {
+ const max = heights.items[y].items[x];
+ // look right
+ var sr: usize = 1; // scenic score to the right
+ var i: usize = x + 1;
+ while (i < lastX) : (i += 1) {
+ if (heights.items[y].items[i] < max) {
+ sr += 1;
+ } else {
+ break;
+ }
+ }
+ // look left
+ var sl: usize = 1;
+ i = x - 1;
+ while (i > 0) : (i -= 1) {
+ if (heights.items[y].items[i] < max) {
+ sl += 1;
+ } else {
+ break;
+ }
+ }
+ // look down
+ var sd: usize = 1;
+ i = y + 1;
+ while (i < lastY) : (i += 1) {
+ if (heights.items[i].items[x] < max) {
+ sd += 1;
+ } else {
+ break;
+ }
+ }
+ // look up
+ var su: usize = 1;
+ i = y - 1;
+ while (i > 0) : (i -= 1) {
+ if (heights.items[i].items[x] < max) {
+ su += 1;
+ } else {
+ break;
+ }
+ }
+ const score = sr * sl * sd * su;
+ if (score > tot) {
+ tot = score;
+ }
+ }
+ }
+ return tot;
+}