Day 11 part 1

const 
  CAVEW = 10
  CAVEH = 10
  DAYS = 100

type
  Energymap = array[CAVEW, array[CAVEH, int]]

var
  cave: Energymap
  flashes: int

proc readFile(fn: string) =
  var j: int
  for line in fn.lines:
    for i in 0..<line.len:
      cave[i][j] = ($line[i]).parseInt
    j.inc

proc inc(em: var Energymap) =
  for y in 0..<CAVEH:
    for x in 0..<CAVEW:
      em[x][y].inc

proc flashOcto(em: var Energymap, x, y: int, increase=false) = 
  if em[x][y] == 0:
    return
  if increase:
    em[x][y].inc
  if em[x][y] < 10:
    return
  em[x][y] = 0
  flashes.inc
  if x-1 >= 0:
    em.flashOcto(x-1, y, true)
    if y-1 >= 0:
      em.flashOcto(x-1, y-1, true)
  if y-1 >= 0:
    em.flashOcto(x, y-1, true)
    if x+1 < CAVEW:
      em.flashOcto(x+1, y-1, true)
  if x+1 < CAVEW:
    em.flashOcto(x+1, y, true)
    if y+1 < CAVEH:
      em.flashOcto(x+1, y+1, true)
  if y+1 < CAVEH:
    em.flashOcto(x, y+1, true)
    if x-1 >= 0:
      em.flashOcto(x-1, y+1, true)

proc flash(em: var Energymap) = 
  for y in 0..<CAVEH:
    for x in 0..<CAVEW:
      em.flashOcto(x, y)

readFile("input.txt")

for i in 1..DAYS:
  cave.inc
  cave.flash

Answer is: 1625