Day 11

11/02.sh

@@ -0,0 +1,68 @@
+#!/bin/bash
+
+i_max=-1
+j_max=0
+octopi=()
+flashes=()
+n_flashes=0
+step=1
+found_step=-1
+while read line; do
+  if [ $i_max -lt 0 ]; then
+    i_max=${#line}
+  fi
+  octopi+=( $(sed 's/\([0-9]\)/\1 /g' <<< $line) )
+  j_max=$((j_max+1))
+done
+
+for i in $(seq 0 $((i_max-1))); do
+  for j in $(seq 0 $((j_max-1))); do
+    flashes+=( 0 )
+  done
+done
+
+check_flash () {
+  local i=$1
+  local j=$2
+  local i_2
+  local j_2
+  if [ ${octopi[$((i+j*i_max))]} -gt 9 ] && [ ${flashes[$((i+j*i_max))]} -eq 0 ]; then
+    n_flashes=$((n_flashes+1))
+    flashes[$((i+j*i_max))]=1
+    for i_2 in $(seq $((i-1)) $((i+1))); do
+      for j_2 in $(seq $((j-1)) $((j+1))); do
+        if [ $i_2 -ge 0 ] && [ $j_2 -ge 0 ] && [ $i_2 -lt $i_max ] && [ $j_2 -lt $j_max ]; then
+          octopi[$((i_2+j_2*i_max))]=$((octopi[i_2+j_2*i_max]+1))
+          check_flash $i_2 $j_2
+        fi
+      done
+    done
+  fi
+}
+
+while [ $found_step -eq -1 ]; do
+  n_flashes=0
+  for i in $(seq 0 $((i_max-1))); do
+    for j in $(seq 0 $((j_max-1))); do
+      octopi[$((i+j*i_max))]=$((octopi[i+j*i_max]+1))
+      flashes[$((i+j*i_max))]=0
+    done
+  done
+  for i in $(seq 0 $((i_max-1))); do
+    for j in $(seq 0 $((j_max-1))); do
+      check_flash $i $j
+    done
+  done
+  for i in $(seq 0 $((i_max-1))); do
+    for j in $(seq 0 $((j_max-1))); do
+      if [ ${octopi[$((i+j*i_max))]} -gt 9 ]; then
+        octopi[$((i+j*i_max))]=0
+      fi
+    done
+  done
+  if [ $n_flashes -eq $((i_max*j_max)) ]; then
+    found_step=$step
+  fi
+  step=$((step+1))
+done
+echo $found_step