🥒 ⭐ 🔑 🎅 🥒 Day 25, Sea Cucumbers did know where the keys are! 🔑 ⭐

Author: natemago

README.md

@@ -1,6 +1,8 @@
 # adventofcode-2021
 :christmas_tree: :santa: Advent Of Code 2021 :anchor: :ship:
 
+![OMG The key was under the sub this whole time :O](calendar.gif)
+
 # Solutions
 
 * [Day 1 - Sonar Sweep :boat: :anchor:](day1-sonar-sweep)
@@ -27,3 +29,4 @@
 * [Day 22 - Reactor Reboot :radioactive: :recycle:](day22-reactor-reboot)
 * [Day 23 - Amphipod :crab: :lobster: :shrimp: :lobster: :crab:](day23-amphipod)
 * [Day 24 - Arithmetic Logic Unit :floppy_disk: :computer: :stop_sign: :fire:](day24-arithmetic-logic-unit)
+* [Day 25 - Sea cucumber :cucumber: :star: :key: :santa: :cucumber:](day25-sea-cucumber)

calendar.gif

@@ -0,0 +1,74 @@
+def read_input(inpf):
+    with open(inpf) as f:
+        sea_map = []
+        for line in f:
+            line = line.strip()
+            if not line:
+                break
+            sea_map.append([c for c in line])
+        return sea_map
+
+def to_state(sea_map):
+    state = {'v': set(), '>': set()}
+    for y, row in enumerate(sea_map):
+        for x, c in enumerate(row):
+            if c in '>v':
+                state[c].add((x, y))
+    return state, len(sea_map[0]), len(sea_map)
+
+
+def move_herd(state, width, height, herd):
+    moving = state[herd]
+    stationary = state['>' if herd == 'v' else 'v']
+    dx, dy = (1, 0) if herd == '>' else (0, 1)
+
+    moved = set()
+    unmoved = set()
+    for x, y in moving:
+        n = ((x+dx)%width, (y+dy)%height)
+        if n in stationary or n in moving:
+            unmoved.add((x, y))
+        else:
+            moved.add(n)
+    ns = {}
+    ns.update(state)
+    ns[herd] = moved.union(unmoved)
+    
+    return ns, len(moved)
+
+def next_state(state, width, height):
+    state, h_moved = move_herd(state, width, height, '>')
+    state, v_moved = move_herd(state, width, height, 'v')
+
+    return state, h_moved or v_moved
+
+    
+def print_state(state, w, h):
+    vert = state['v']
+    hor = state['>']
+    for y in range(h):
+        for x in range(w):
+            n = (x, y)
+            if n in vert:
+                print('V', end='')
+            elif n in hor:
+                print('>', end='')
+            else:
+                print('.', end='')
+        print()
+
+
+
+def part1(sea_map):
+    state, width, height = to_state(sea_map)
+    step = 0
+    while True:
+        state, has_moved = next_state(state, width, height)
+        step += 1
+        if not has_moved:
+            break
+    return step
+
+print(('\033[33m' + '★' + '\033[0m')*50)
+print('\033[32mThe cucumbers stop moving after: \033[0m\033[31m', part1(read_input('input')), '\033[0m\033[32msteps.\033[0m')
+print(('\033[33m' + '★' + '\033[0m' + '\033[32m' + '★' + '\033[0m')*25)