Finished day 11.

2021/11/data

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+1254117228
+4416873224
+8354381553
+1372637614
+5586538553
+7213333427
+3571362825
+1681126243
+8718312138
+5254266347

2021/11/example_data

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+5483143223
+2745854711
+5264556173
+6141336146
+6357385478
+4167524645
+2176841721
+6882881134
+4846848554
+5283751526

2021/11/main.py

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+grid = []
+to_flash = []
+
+for line in open('data', 'r'):
+    grid_line = []
+    for ch in line.strip():
+        grid_line.append(int(ch))
+    grid.append(grid_line)
+
+flashed = 0
+for step in range(0, 100):
+    # Step 1: Increment
+    for y in range(0, len(grid)):
+        for x in range(0, len(grid[y])):
+            grid[y][x] += 1
+            if(grid[y][x] > 9):
+                to_flash.append(tuple([y, x]))
+
+    if(len(to_flash) == len(grid) * len(grid[0])):
+        print('all flash step #', step + 1)
+    # Step 2: Flash
+    while(len(to_flash)):
+        cell = to_flash[-1] # take the last one
+        to_flash.pop() # remove
+        flashed += 1 # count
+        for y in range(-1, 2):
+            new_y = cell[0] + y
+            if(new_y >= 0 and new_y < len(grid)): # in bounds
+                for x in range(-1, 2):
+                    new_x = cell[1] + x
+                    if(new_x >= 0 and new_x < len(grid[y])): # in bounds
+                        grid[new_y][new_x] += 1
+                        if(grid[new_y][new_x] == 10): # JUST flashed
+                            to_flash.append(tuple([new_y, new_x]))
+
+    # Step 3: Reset (if flashed)
+    for y in range(0, len(grid)):
+        for x in range(0, len(grid[y])):
+            if(grid[y][x] > 9):
+                grid[y][x] = 0
+
+    print('Step #', (step + 1), ': ', flashed)

2021/11/main2.py

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+grid = []
+to_flash = []
+
+for line in open('data', 'r'):
+    grid_line = []
+    for ch in line.strip():
+        grid_line.append(int(ch))
+    grid.append(grid_line)
+
+flashed = 0
+step = 0
+#for step in range(0, 100):
+while(True):
+    # Step 1: Increment
+    for y in range(0, len(grid)):
+        for x in range(0, len(grid[y])):
+            grid[y][x] += 1
+            if(grid[y][x] > 9):
+                to_flash.append(tuple([y, x]))
+
+    # Step 2: Flash
+    prior_flash = flashed
+    while(len(to_flash)):
+        cell = to_flash[-1] # take the last one
+        to_flash.pop() # remove
+        flashed += 1 # count
+        for y in range(-1, 2):
+            new_y = cell[0] + y
+            if(new_y >= 0 and new_y < len(grid)): # in bounds
+                for x in range(-1, 2):
+                    new_x = cell[1] + x
+                    if(new_x >= 0 and new_x < len(grid[y])): # in bounds
+                        grid[new_y][new_x] += 1
+                        if(grid[new_y][new_x] == 10): # JUST flashed
+                            to_flash.append(tuple([new_y, new_x]))
+
+    # PART TWO ANSWER
+    if(flashed - prior_flash == len(grid) * len(grid[0])):
+        print('all flash step #', step + 1)
+        break
+
+    # Step 3: Reset (if flashed)
+    for y in range(0, len(grid)):
+        for x in range(0, len(grid[y])):
+            if(grid[y][x] > 9):
+                grid[y][x] = 0
+
+    print('Step #', (step + 1), ': ', flashed)
+    step += 1