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14-2
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@milanaleksic
milanaleksic committed Dec 21, 2023
1 parent 0c5fe7e commit fca5135
Showing 1 changed file with 131 additions and 30 deletions.
161 changes: 131 additions & 30 deletions src/day14.zig
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Original file line number Diff line number Diff line change
Expand Up @@ -74,9 +74,10 @@ const Data = struct {
}

pub fn moveToNorth(self: *Self) void {
for (0..self.rows.items.len) |x| {
const dim: usize = self.rows.items.len;
for (0..dim) |x| {
var foundation: usize = 0;
for (0..self.rows.items.len) |y| {
for (0..dim) |y| {
var cell = self.rows.items[y].items[x];
switch (cell.nodeType) {
NodeType.CubeRock => foundation = y + 1,
Expand All @@ -94,26 +95,85 @@ const Data = struct {
}
}

// pub fn moveToSouth(self: *Self) void {
// for (0..self.rows.items.len) |x| {
// var foundation: usize = self.rows.items.len - 1;
// for (self.rows.items, 0..) |*row, y| {
// var cell = row.items[x];
// switch (cell.nodeType) {
// NodeType.CubeRock => foundation = y + 1,
// NodeType.RoundRock => {
// if (foundation < y) {
// // print("Moving item from {d} to {d}\n", .{ y, foundation });
// self.rows.items[foundation].items[x].nodeType = NodeType.RoundRock;
// self.rows.items[y].items[x].nodeType = NodeType.Empty;
// }
// foundation += 1;
// },
// else => {},
// }
// }
// }
// }
pub fn moveToSouth(self: *Self) void {
const dim: usize = self.rows.items.len;
for (0..dim) |x| {
var foundation: usize = dim - 1;
for (0..dim) |yiter| {
const y = dim - yiter - 1;
var cell = self.rows.items[y].items[x];
switch (cell.nodeType) {
NodeType.CubeRock => {
if (y > 0) {
foundation = y - 1;
}
},
NodeType.RoundRock => {
if (foundation > y) {
// print("Moving item from {d} to {d}\n", .{ y, foundation });
self.rows.items[foundation].items[x].nodeType = NodeType.RoundRock;
self.rows.items[y].items[x].nodeType = NodeType.Empty;
}
if (foundation > 0) {
foundation -= 1;
}
},
else => {},
}
}
}
}

pub fn moveToWest(self: *Self) void {
const dim: usize = self.rows.items.len;
for (0..dim) |y| {
var foundation: usize = 0;
for (0..dim) |x| {
var cell = self.rows.items[y].items[x];
switch (cell.nodeType) {
NodeType.CubeRock => foundation = x + 1,
NodeType.RoundRock => {
if (foundation < x) {
// print("Moving item from {d} to {d}\n", .{ x, foundation });
self.rows.items[y].items[foundation].nodeType = NodeType.RoundRock;
self.rows.items[y].items[x].nodeType = NodeType.Empty;
}
foundation += 1;
},
else => {},
}
}
}
}

pub fn moveToEast(self: *Self) void {
const dim: usize = self.rows.items.len;
for (0..dim) |y| {
var foundation: usize = dim - 1;
for (0..dim) |xiter| {
const x = dim - xiter - 1;
var cell = self.rows.items[y].items[x];
switch (cell.nodeType) {
NodeType.CubeRock => {
if (x > 0) {
foundation = x - 1;
}
},
NodeType.RoundRock => {
if (foundation > x) {
// print("Moving item from {d} to {d}\n", .{ y, foundation });
self.rows.items[y].items[foundation].nodeType = NodeType.RoundRock;
self.rows.items[y].items[x].nodeType = NodeType.Empty;
}
if (foundation > 0) {
foundation -= 1;
}
},
else => {},
}
}
}
}

pub fn calculate(self: *Self) usize {
var sum: usize = 0;
Expand Down Expand Up @@ -176,15 +236,56 @@ pub fn part2(allocator: std.mem.Allocator, list: std.ArrayList([]const u8)) !usi
var data = try Data.init(allocator, list);
defer data.deinit();

for (0..100) |_| {
var cycleDetection: std.ArrayList(usize) = std.ArrayList(usize).init(allocator);
defer cycleDetection.deinit();

const target: usize = 1_000_000_000;

for (1..target + 1) |i| {
_ = i;
data.moveToNorth();
// data.moveToWest();
// data.moveToSouth();
// data.moveToEast();
print("{d}\n", .{data.calculate()});
data.moveToWest();
data.moveToSouth();
data.moveToEast();
try cycleDetection.append(data.calculate());
if (isCycleDetectable(cycleDetection)) |cycle| {
print("Cycle detected: {}\n", .{cycle});
const numerator = target - cycle.begin;
const denominator = cycle.end - cycle.begin + 1;
// print("numerator={d}, denominator={d}\n", .{ numerator, denominator });
return cycleDetection.items[cycle.begin + @mod(numerator, denominator) - 1];
}
// print("{d} -> {d}\n", .{ i, data.calculate() });
}
@panic("no solution found");
}

return data.calculate();
const Cycle = struct {
begin: usize,
end: usize,
};

fn isCycleDetectable(cycleDetection: std.ArrayList(usize)) ?Cycle {
if (cycleDetection.items.len < 10) {
return null;
}
// minimum size of a cycle we can detect
const cycle: usize = 5;
for (cycle..cycleDetection.items.len) |i| {
if (3 * i > cycleDetection.items.len - 1) {
continue;
}
var x1 = cycleDetection.items.len - i - 1;
var x2 = cycleDetection.items.len - 2 * i - 1;
var x3 = cycleDetection.items.len - 3 * i - 1;
if (cycleDetection.items[x1] == cycleDetection.items[x2] and cycleDetection.items[x2] == cycleDetection.items[x3]) {
return Cycle{
.begin = x2,
.end = x1 - 1,
};
}
}
return null;
}

test "part 2 test 1" {
Expand All @@ -202,7 +303,7 @@ test "part 2 test 1" {
);
defer list.deinit();

const testValue: usize = try part1(std.testing.allocator, list);
const testValue: usize = try part2(std.testing.allocator, list);
try std.testing.expectEqual(testValue, 64);
}

Expand All @@ -211,5 +312,5 @@ test "part 2 full" {
defer data.deinit();

const testValue: usize = try part2(std.testing.allocator, data.lines);
try std.testing.expectEqual(testValue, 0);
try std.testing.expectEqual(testValue, 118747);
}

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