2022 - Day 9

Author: Benbb96

python/2022/day9/day9.py

@@ -0,0 +1,88 @@
+from python.download_input import get_input_content
+
+
+DIRECTIONS = {
+    'U': (0, -1),
+    'R': (1, 0),
+    'D': (0, 1),
+    'L': (-1, 0),
+}
+
+
+def move_tail(hx: int, hy: int, tx: int, ty: int) -> tuple[int, int]:
+    if hy == ty:
+        if hx - tx > 1:
+            tx += 1
+        elif hx - tx < -1:
+            tx -= 1
+    elif hx == tx:
+        if hy - ty > 1:
+            ty += 1
+        elif hy - ty < -1:
+            ty -= 1
+    else:
+        if hx - tx > 1:
+            tx += 1
+            if hy > ty:
+                ty += 1
+            else:
+                ty -= 1
+        elif hx - tx < -1:
+            tx -= 1
+            if hy > ty:
+                ty += 1
+            else:
+                ty -= 1
+        elif hy - ty > 1:
+            ty += 1
+            if hx > tx:
+                tx += 1
+            else:
+                tx -= 1
+        elif hy - ty < -1:
+            ty -= 1
+            if hx > tx:
+                tx += 1
+            else:
+                tx -= 1
+
+    return tx, ty
+
+
+def first(data):
+    hx, hy, tx, ty = 0, 0, 0, 0
+    tail_positions = set()
+    for line in data:
+        d, v = line.split()
+        v = int(v)
+        for _ in range(v):
+            hx, hy = (hx + DIRECTIONS[d][0], hy + DIRECTIONS[d][1])
+            tx, ty = move_tail(hx, hy, tx, ty)
+            tail_positions.add((tx, ty))
+
+    return len(tail_positions)
+
+
+def second(data):
+    knot_positions = [(0, 0) for _ in range(10)]
+    tail_positions = set()
+    for line in data:
+        d, v = line.split()
+        v = int(v)
+        for _ in range(v):
+            knot_positions[0] = (knot_positions[0][0] + DIRECTIONS[d][0], knot_positions[0][1] + DIRECTIONS[d][1])
+            for i in range(9):
+                hx, hy = knot_positions[i]
+                tx, ty = knot_positions[i+1]
+                knot_positions[i + 1] = move_tail(hx, hy, tx, ty)
+            tail_positions.add(knot_positions[-1])
+
+    return len(tail_positions)
+
+
+if __name__ == "__main__":
+    content = get_input_content(__file__)
+
+    print(f'Le résultat de la première partie est :\n{first(content)}')
+
+    print(f'Le résultat de la deuxième partie est :\n{second(content)}')