Lua岛屿染色：网格连通块的计数扫描

local function countIslands(grid)
    local n = 0
    for r = 1, #grid do
        for c = 1, #grid[r] do
            if grid[r][c] == 1 then n = n + 1 end   -- 相连的重复计数
        end
    end
    return n
end

local function countIslands(grid)
    local n = 0
    for r = 1, #grid do
        for c = 1, #grid[r] do
            if grid[r][c] == 1 then
                n = n + 1
                local stack = {{r, c}}
                while #stack > 0 do
                    local p = table.remove(stack)
                    grid[p[1]][p[2]] = 2    -- 整片染成2
                    for _, d in ipairs({{-1,0},{1,0},{0,-1},{0,1}}) do
                        local nr, nc = p[1]+d[1], p[2]+d[2]
                        if grid[nr] and grid[nr][nc] == 1 then
                            stack[#stack+1] = {nr, nc}
                        end
                    end
                end
            end
        end
    end
    return n
end
sendmsg(actor, 1, "矿区连通矿脉 " .. countIslands(GRID) .. " 片")