Day 17

17.py

@@ -0,0 +1,116 @@
+lines = [line.split() for line in open("17.input")]
+
+jets = lines[0][0]
+
+blocks = [
+        [(0, 0), (1, 0), (2, 0), (3, 0)],
+        [(1, 0), (0, 1), (1, 1), (2, 1), (1, 2)],
+        [(2, 0), (2, 1), (0, 2), (1, 2), (2, 2)],
+        [(0, 0), (0, 1), (0, 2), (0, 3)],
+        [(0, 0), (0, 1), (1, 0), (1, 1)],
+        ]
+
+def show(occupied):
+    stack_height = min([pos[1] for pos in occupied] + [0])
+
+    for y in range(stack_height, 0):
+        print("|", end='')
+        for x in range(7):
+            if (x, y) in occupied:
+                print("#", end='')
+            else:
+                print(".", end='')
+        print("|")
+    print("-" * 9)
+
+
+def add(a, b):
+    return (a[0] + b[0], a[1] + b[1])
+
+def run(target_blocks):
+    occupied = set([(x, 0) for x in range(9)])
+    jet_idx = 0
+
+    combos = set()
+    target = None
+    found = []
+
+    block_count = 0
+
+    time_skip = False
+
+    while block_count < target_blocks:
+        block_idx = block_count % len(blocks)
+
+        stack_height = min([pos[1] for pos in occupied] + [0])
+
+        if not found:
+            if (jet_idx, block_idx) in combos:
+                # Set our target for time skip
+                target = (jet_idx, block_idx)
+                found.append((block_count, stack_height))
+                print("Found repetition after", block_count, "blocks")
+            else:
+                combos.add((jet_idx, block_idx))
+        elif not time_skip:
+            if (jet_idx, block_idx) == target:
+                print("Found again after", block_count)
+                found.append((block_count, stack_height))
+                if len(found) == 2:
+                    chunk_blocks = found[-1][0] - found[-2][0]
+                    chunk_height = -(found[-1][1] - found[-2][1])
+                    extra_chunks = (target_blocks - block_count) // chunk_blocks
+                    extra_blocks = extra_chunks * chunk_blocks
+                    block_count += extra_blocks
+                    extra_height = extra_chunks * chunk_height
+                    print(f"Performing time-skip (+{extra_blocks} blocks, +{extra_height} height).")
+                    occupied = {add(pos, (0, -extra_height)) for pos in occupied}
+                    time_skip = True
+                    continue
+
+
+        block = blocks[block_idx]
+
+        b_height = max(pos[1] for pos in block)
+
+        start_pos = (2, stack_height - b_height - 4)
+
+        block = [add(pos, start_pos) for pos in block]
+
+        #show(occupied.union(block))
+
+        while True:
+            # Jetting
+            max_x = max(pos[0] for pos in block)
+            min_x = min(pos[0] for pos in block)
+
+            jet = jets[jet_idx]
+            jet_idx += 1
+            jet_idx = jet_idx % len(jets)
+
+            if min_x > 0 and jet == '<':
+                next_block = {add(pos, (-1, 0)) for pos in block}
+            elif max_x < 6 and jet == '>':
+                next_block = {add(pos, (1, 0)) for pos in block}
+
+            if not next_block.intersection(occupied):
+                block = next_block
+
+            # Falling
+            next_block = {add(pos, (0, 1)) for pos in block}
+
+            if next_block.intersection(occupied):
+                occupied = occupied.union(block)
+                break
+            else:
+                block = next_block
+
+        block_count += 1
+
+    stack_height = min([pos[1] for pos in occupied] + [0])
+    return -stack_height
+
+
+print("Part 1:", run(2022))
+print("Part 2:", run(1000000000000))
+