diff options
Diffstat (limited to '16')
| -rw-r--r-- | 16/1.lua | 89 |
1 files changed, 89 insertions, 0 deletions
diff --git a/16/1.lua b/16/1.lua new file mode 100644 index 0000000..f136da8 --- /dev/null +++ b/16/1.lua @@ -0,0 +1,89 @@ +function read_matrix(filename) + local fp = io.open(filename, 'r') + local lines = {} + while true do + local line = fp:read() + if (not line) or #line == 0 then break end + table.insert(lines, line) + end + return lines +end + +local layout = read_matrix('input') +local height = #layout +local width = #layout[1] + +local trace_set = {} +local active_set = {} +local count = 0 + +function trace(layout, x, y, direction) + if x < 1 or x > width then return nil end + if y < 1 or y > width then return nil end + + trace_key = x..','..y..','..direction + if trace_set[trace_key] == nil then + trace_set[trace_key] = 1 + else + return nil + end + + if active_set[x..','..y] == nil then + active_set[x..','..y] = 1 + count = count + 1 + end + -- trace next + local cur = layout[y]:sub(x,x) + if cur == '.' then + if direction == 'E' then + trace(layout, x+1, y, direction) + elseif direction == 'W' then + trace(layout, x-1, y, direction) + elseif direction == 'N' then + trace(layout, x, y-1, direction) + elseif direction == 'S' then + trace(layout, x, y+1, direction) + end + elseif cur == '-' then + if direction == 'E' then + trace(layout, x+1, y, direction) + elseif direction == 'W' then + trace(layout, x-1, y, direction) + elseif direction == 'N' or direction == 'S' then + trace(layout, x+1, y, 'E') + trace(layout, x-1, y, 'W') + end + elseif cur == '|' then + if direction == 'E' or direction == 'W' then + trace(layout, x, y-1, 'N') + trace(layout, x, y+1, 'S') + elseif direction == 'N' then + trace(layout, x, y-1, direction) + elseif direction == 'S' then + trace(layout, x, y+1, direction) + end + elseif cur == '/' then + if direction == 'E' then + trace(layout, x, y-1, 'N') + elseif direction == 'W' then + trace(layout, x, y+1, 'S') + elseif direction == 'N' then + trace(layout, x+1, y, 'E') + elseif direction == 'S' then + trace(layout, x-1, y, 'W') + end + elseif cur == '\\' then + if direction == 'E' then + trace(layout, x, y+1, 'S') + elseif direction == 'W' then + trace(layout, x, y-1, 'N') + elseif direction == 'N' then + trace(layout, x-1, y, 'W') + elseif direction == 'S' then + trace(layout, x+1, y, 'E') + end + end +end + +trace(layout, 1, 1, 'E') +print(count)
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