Day 12

[advent-of-code-2020.git] / day12 / ship-2.py

diff --git a/day12/ship-2.py b/day12/ship-2.py
new file mode 100755 (executable)
index 0000000..a8ebdad
--- /dev/null
+++ b/day12/ship-2.py
@@ -0,0 +1,80 @@
+#!/usr/bin/python3
+
+import sys
+
+waypoint_horz=10
+waypoint_vert=1
+directions=["E", "S", "W", "N"]
+ship_x=0
+ship_y=0
+
+def do_waypoint_move(direction, amount):
+    global waypoint_horz
+    global waypoint_vert
+    if direction in ["E", "W"]:
+        if direction == "W":
+            amount=amount*-1
+        waypoint_horz+=amount
+    elif direction in ["N", "S"]:
+        if direction == "S":
+            amount=amount*-1
+        waypoint_vert+=amount
+
+def turn(amount,multiplier):
+    global waypoint_horz,waypoint_vert
+    steps=int(amount / 90)
+    steps=steps * multiplier
+
+    print("Started at: {},{} rotating {}".format(waypoint_horz,waypoint_vert,amount*multiplier))
+    print("Steps: {}".format(steps))
+    # translate left in to moves right
+    if (steps < 0):
+        steps=4+steps
+
+    if steps == 4 or steps == 0:
+        return
+
+    print("Steps: {}".format(steps))
+
+    # and now we just step round that many steps to the right
+    # now 1,2 will go round to 2,-1, i.e. x,y -> y,-x
+    for step in range(steps):
+        temp=waypoint_vert
+        waypoint_vert=(waypoint_horz*-1)
+        waypoint_horz=temp
+
+    print("Ended at: {},{}".format(waypoint_horz,waypoint_vert))
+
+def do_ship_move(amount):
+    global waypoint_horz,waypoint_vert,ship_x,ship_y
+    print("Waypoint {},{}, Ship {},{}, Amount {}".format(waypoint_horz, waypoint_vert, ship_x, ship_y, amount))
+    ship_x+=(amount*waypoint_horz)
+    ship_y+=(amount*waypoint_vert)
+    print("Ship {},{}".format(ship_x, ship_y))
+
+def turn_right(amount):
+    turn(amount, 1)
+
+def turn_left(amount):
+    turn(amount, -1)
+
+filename="input.txt"
+
+if len(sys.argv) > 1:
+    filename=sys.argv[1]
+
+for line in open(filename, "r"):
+    line=line.rstrip()
+    command=line[0]
+    amount=int(line[1:])
+
+    if command in [ "N", "S", "E", "W" ]:
+        do_waypoint_move(command, amount)
+    elif command == "R":
+        turn_right(amount)
+    elif command == "L":
+        turn_left(amount)
+    elif command == "F":
+        do_ship_move(amount)
+
+print("Moved to {}, {} - MD: {}".format(ship_x,ship_y,(abs(ship_x)+abs(ship_y))))