2022 - Day 9 part 2

2022/9/9_2.py

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+#!/usr/bin/env python
+# 2022 - Advent Of Code 9 part2
+
+import math
+
+# file = 'input_example.txt'
+# file = 'input_example2.txt'
+file = 'input.txt'
+
+
+visited_pos = [[0, 0]]
+
+
+def parse_file(input_file):
+    moves = []
+    with open(input_file, encoding="utf-8") as f:
+        for line in f.readlines():
+            d, u = line.strip().split(' ')
+            moves.append((d, int(u)))
+        return moves
+
+
+def col_round(x):
+    frac = x - int(x)
+    if frac < 0.5:
+        return math.floor(x)
+    return math.ceil(x)
+
+
+def move_tail(h, t, i):
+    vx = h[0] - t[0]
+    vy = h[1] - t[1]
+
+    vlen = round(math.sqrt(vx * vx + vy * vy))
+    head_tail_dist = vlen
+
+    if head_tail_dist > 1:
+        nx = col_round(vx / vlen)
+        ny = col_round(vy / vlen)
+        t[0] += nx
+        t[1] += ny
+        if i == 9:
+            v_list = [t[0], t[1]]
+            if v_list not in visited_pos:
+                visited_pos.append(v_list)
+
+
+def move_rope(r):
+    for i in range(1, 10):
+        move_tail(r[i-1], r[i], i)
+
+
+head_moves = parse_file(file)
+print(head_moves)
+rope = [[0, 0] for _ in range(0, 10)]
+
+
+for m in head_moves:
+    if m[0] == 'R':
+        print(f'right: {m[1]}')
+        for _ in range(0, m[1]):
+            rope[0][0] += 1
+            move_rope(rope)
+    if m[0] == 'L':
+        print(f'left: {m[1]}')
+        for _ in range(0, m[1]):
+            rope[0][0] -= 1
+            move_rope(rope)
+    if m[0] == 'U':
+        print(f'up: {m[1]}')
+        for _ in range(0, m[1]):
+            rope[0][1] += 1
+            move_rope(rope)
+    if m[0] == 'D':
+        print(f'down: {m[1]}')
+        for _ in range(0, m[1]):
+            rope[0][1] -= 1
+            move_rope(rope)
+
+print(visited_pos)
+print(len(visited_pos))

2022/9/input_example2.txt

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+R 5
+U 8
+L 8
+D 3
+R 17
+D 10
+L 25
+U 20