diff --git a/2021/inputs/day_11 b/2021/inputs/day_11
new file mode 100644
index 0000000..1d764ea
--- /dev/null
+++ b/2021/inputs/day_11
@@ -0,0 +1,10 @@
+4836484555
+4663841772
+3512484556
+1481547572
+7741183422
+8683222882
+4215244233
+1544712171
+5725855786
+1717382281
diff --git a/2021/solutions/day_11.py b/2021/solutions/day_11.py
new file mode 100644
index 0000000..1d0650d
--- /dev/null
+++ b/2021/solutions/day_11.py
@@ -0,0 +1,108 @@
+"""AOC Day 11"""
+
+import pathlib
+import time
+
+TEST_INPUT = """5483143223
+2745854711
+5264556173
+6141336146
+6357385478
+4167524645
+2176841721
+6882881134
+4846848554
+5283751526"""
+
+def read_input(input_path: str) -> str:
+    """take input file path and return a str with the file's content"""
+    with open(input_path, 'r') as input_file:
+        input_data = input_file.read().strip()
+        return input_data
+
+def extract(input_data: str) -> list:
+    """take input data and return the appropriate data structure"""
+    lines = input_data.split('\n')
+    return list(list(map(int, row)) for row in lines)
+
+def neighbors(row: int, column: int, height: int, width: int) -> tuple:
+    deltas = (
+        (1, 0), (-1, 0),
+        (0, 1), (0, -1),
+        (1, 1), (1, -1),
+        (-1, 1), (-1, -1)
+    )
+
+    for delta_row, delta_column in deltas:
+        inc_row, inc_column = (row + delta_row, column + delta_column)
+        if 0 <= inc_row < height and 0 <= inc_column < width:
+            yield inc_row, inc_column
+
+def flash(grid: list, row: int, column: int, height: int, width: int):
+    if grid[row][column] > 9:
+        grid[row][column] = -1
+        for n_row, n_column in neighbors(row, column, height, width):
+            if grid[n_row][n_column] != -1:
+                grid[n_row][n_column] += 1
+                flash(grid, n_row, n_column, height, width)
+
+def step(grid: list, height: int, width: int) -> int:
+    flashes = 0
+
+    for row in range(height):
+        for column in range(width):
+            grid[row][column] += 1
+
+    for row in range(height):
+        for column in range(width):
+            flash(grid, row, column, height, width)
+    
+    for row in range(height):
+        for column in range(width):
+            if grid[row][column] == -1:
+                grid[row][column] = 0
+                flashes += 1
+    
+    return flashes
+
+def part1(grid: list) -> int:
+    """part1 solver take the entries and return the part1 solution"""
+    height, width = len(grid), len(grid[0])
+    flashes = sum(step(grid, height, width) for _ in range(100))
+
+    return flashes
+
+def part2(grid: list) -> int:
+    """part2 solver take the entries and return the part2 solution"""
+    num_step = 101
+    height, width = len(grid), len(grid[0])
+    num_cells = height * width
+    while True:
+        if step(grid, height, width) == num_cells:
+            return num_step
+        num_step += 1
+
+
+def test_input_day_11():
+    """pytest testing function"""
+    entries = extract(TEST_INPUT)
+    assert part1(entries) == 1656
+    assert part2(entries) == 195
+
+def test_bench_day_11(benchmark):
+    """pytest-benchmark function"""
+    benchmark(main)
+
+def main():
+    """main function"""
+    input_path = str(pathlib.Path(__file__).resolve().parent.parent) + "/inputs/" + str(pathlib.Path(__file__).stem)
+    start_time = time.time()
+    input_data = read_input(input_path)
+    entries = extract(input_data)
+    print("Part 1: %d" % part1(entries))
+    print("Part 2: %d" % part2(entries))
+    end_time = time.time()
+    print("Execution time: %f" % (end_time-start_time))
+
+if __name__ == "__main__":
+    main()