[py] Port 2016_01

py/aoc/y2016/d01.py

@@ -0,0 +1,73 @@
+def load_steps(inputstr):
+    steps = []
+    for step in inputstr[:-1].split(","):
+        step = step.strip()
+        step = (step[0], int(step[1:]))
+        steps.append(step)
+    return steps
+
+
+# PART 1
+
+
+def turn(direction, where):
+    dir_x, dir_y = direction
+
+    if where == "R":
+        return (dir_y, -dir_x)
+    elif where == "L":
+        return (-dir_y, dir_x)
+    else:
+        raise Exception("HEY! Don't do that!")
+
+
+def manhattan(position):
+    x, y = position
+    return abs(x) + abs(y)
+
+
+def find_distance(steps):
+    pos_x, pos_y = 0, 0
+    direction = (1, 0)
+
+    for step in steps:
+        where, amount = step
+        direction = turn(direction, where)
+        dir_x, dir_y = direction
+        pos_x += dir_x * amount
+        pos_y += dir_y * amount
+
+    return manhattan((pos_x, pos_y))
+
+
+# PART 2
+
+
+def first_visited_twice(steps):
+    pos_x, pos_y = 0, 0
+    direction = (1, 0)
+    visited = {(pos_x, pos_y)}
+
+    for step in steps:
+        where, amount = step
+        direction = turn(direction, where)
+        dir_x, dir_y = direction
+
+        for i in range(amount):
+            pos_x += dir_x
+            pos_y += dir_y
+            position = (pos_x, pos_y)
+
+            if position in visited:
+                return position
+            else:
+                visited.add(position)
+
+
+def solve(inputstr):
+    steps = load_steps(inputstr)
+    distance = find_distance(steps)
+    print(f"Part 1: {distance}")
+    pos = first_visited_twice(steps)
+    distance_2 = manhattan(pos)
+    print(f"Part 2: {distance_2}")