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2022 Day 24 part 2 Python

This commit is contained in:
Luke Hubmayer-Werner 2023-01-04 18:48:17 +10:30
parent 5702c0eb17
commit c02c143dea
1 changed files with 53 additions and 12 deletions
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63
2022/day24.py
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@ -40,10 +40,12 @@ def sim(lines):
seen_states = set() seen_states = set()
state_stack = [(0,-1,0)] state_stack = [(0,-1,0)]
def try_add_state(col: int, row: int, time: int): def try_add_state(col: int, row: int, time: int):
if col < 0 or col >= width or row < -1 or row >= height: if col < 0 or col >= width or row < -1 or row > height:
return return
if row == -1 and col != 0: if row == -1 and col != 0:
return return
if row == height and col != width-1:
return
if not position_free(col, row, time): if not position_free(col, row, time):
return return
triple = (col, row, time) triple = (col, row, time)
@ -51,28 +53,67 @@ def sim(lines):
seen_states.add(triple) seen_states.add(triple)
state_stack.append(triple) state_stack.append(triple)
best_time = None best_time = 1_000_000
goal = (width-1, height) goal = (width-1, height) # End position
print('Moving from start to end')
while state_stack: while state_stack:
col, row, t = state_stack.pop() col, row, t = state_stack.pop()
t1 = t + 1 t1 = t + 1
goal_distance = goal[0]-col + goal[1]-row # Manhattan distance goal_distance = abs(goal[0]-col) + abs(goal[1]-row) # Manhattan distance
if goal_distance == 1: # we're right next to the goal! move there and end this trail if goal_distance == 1: # we're right next to the goal! move there and end this trail
if best_time:
best_time = min(best_time, t1) best_time = min(best_time, t1)
else:
best_time = t1
continue continue
if best_time and (t + goal_distance > best_time): if t + goal_distance > best_time:
continue continue
try_add_state(col, row, t1)
try_add_state(col-1, row, t1) try_add_state(col-1, row, t1)
try_add_state(col, row-1, t1) try_add_state(col, row-1, t1)
try_add_state(col, row, t1)
try_add_state(col+1, row, t1) try_add_state(col+1, row, t1)
try_add_state(col, row+1, t1) try_add_state(col, row+1, t1)
return best_time p1 = best_time
state_stack = [(width-1, height, best_time)]
seen_states.clear()
best_time = 1_000_000
goal = (0, -1) # Starting position
print('Moving from end to start')
while state_stack:
col, row, t = state_stack.pop()
t1 = t + 1
goal_distance = abs(goal[0]-col) + abs(goal[1]-row) # Manhattan distance
if goal_distance == 1: # we're right next to the goal! move there and end this trail
best_time = min(best_time, t1)
continue
if t + goal_distance > best_time:
continue
try_add_state(col+1, row, t1)
try_add_state(col, row+1, t1)
try_add_state(col, row, t1)
try_add_state(col-1, row, t1)
try_add_state(col, row-1, t1)
state_stack = [(0,-1,best_time)]
seen_states.clear()
best_time = 1_000_000
goal = (width-1, height) # End position
print('Moving from start to end (2)')
while state_stack:
col, row, t = state_stack.pop()
t1 = t + 1
goal_distance = abs(goal[0]-col) + abs(goal[1]-row) # Manhattan distance
if goal_distance == 1: # we're right next to the goal! move there and end this trail
best_time = min(best_time, t1)
continue
if t + goal_distance > best_time:
continue
try_add_state(col-1, row, t1)
try_add_state(col, row-1, t1)
try_add_state(col, row, t1)
try_add_state(col+1, row, t1)
try_add_state(col, row+1, t1)
return p1, best_time
print(sim(sample_lines)) print(sim(sample_lines))
print(sim(lines)) print(sim(lines))