diff --git a/day11/input.txt b/day11/input.txt
new file mode 100644
index 0000000..c671d4a
--- /dev/null
+++ b/day11/input.txt
@@ -0,0 +1,10 @@
+6617113584
+6544218638
+5457331488
+1135675587
+1221353216
+1811124378
+1387864368
+4427637262
+6778645486
+3682146745
diff --git a/day11/solution.py b/day11/solution.py
new file mode 100644
index 0000000..a9c57c9
--- /dev/null
+++ b/day11/solution.py
@@ -0,0 +1,75 @@
+import time
+import numpy as np
+
+def incnflash(i, j, m, flashes):
+    m[i, j] += 1
+    if m[i, j] > 9 and not flashes[i, j]:
+        flashes[i, j] = True
+        flash(i, j, m, flashes)
+
+
+def flash(i, j, m, flashes):
+    up = i > 0
+    left = j > 0
+    down = i < m.shape[0] - 1
+    right = j < m.shape[1] - 1
+    if up:
+        incnflash(i-1, j, m, flashes)
+        if left:
+            incnflash(i-1, j-1, m, flashes)
+        if right:
+            incnflash(i-1, j+1, m, flashes)
+    if down:
+        incnflash(i+1, j, m, flashes)
+        if left:
+            incnflash(i+1, j-1, m, flashes)
+        if right:
+            incnflash(i+1, j+1, m, flashes)
+    if left:
+        incnflash(i, j-1, m, flashes)
+    if right:
+        incnflash(i, j+1, m, flashes)
+
+def do_step(m):
+    m += 1
+    flashes = m > 9
+    for i, j in np.argwhere(flashes):
+        flash(i, j, m, flashes)
+    m[flashes] = 0
+    return np.sum(flashes)
+
+def calc_steps(m, steps):
+    res = 0
+    for i in range(steps):
+        res += do_step(m)
+    return res
+
+def calc_steps2(m):
+    res = 0
+    flashes = 0
+    while flashes < m.size:
+        flashes = do_step(m)
+        res += 1
+    return res
+
+def part1(input):
+    m = np.asarray([[int(x) for x in line.strip()] for line in input])
+    return calc_steps(m, 100)
+
+def part2(input):
+    m = np.asarray([[int(x) for x in line.strip()] for line in input])
+    return calc_steps2(m)
+
+def main():
+    with open("day11/input.txt") as f:
+        input =  f.readlines()
+        t0 = time.perf_counter_ns()
+        print(f"solution for part 1 is: {part1(input)}")
+        t1 = time.perf_counter_ns()
+        print(f"part 1 took {t1-t0} ns")
+        print(f"solution for part 2 is: {part2(input)}")
+        t2 = time.perf_counter_ns()
+        print(f"part 2 took {t2-t1} ns")
+
+if __name__ == "__main__":
+    main()
\ No newline at end of file
diff --git a/day11/test_input.txt b/day11/test_input.txt
new file mode 100644
index 0000000..03743f6
--- /dev/null
+++ b/day11/test_input.txt
@@ -0,0 +1,10 @@
+5483143223
+2745854711
+5264556173
+6141336146
+6357385478
+4167524645
+2176841721
+6882881134
+4846848554
+5283751526