# _*_ coding:utf-8 _*_  route_stack = [[0,0]] route_history = [[0,0]] source=[[0,0,1,0,1],[1,0,0,0,1],[0,0,1,1,0],[0,1,0,0,0],[0,0,0,1,0]] def up(location):   #橫坐標為0，無法再向上走   if location[1] == 0:     return False   else:     new_location = [location[0],location[1]-1]     #已經嘗試過的點不會嘗試第二次     if new_location in route_history:       return False     #碰到墻不走     elif source[new_location[0]][new_location[1]] == 1:       return False     else:       route_stack.append(new_location)       route_history.append(new_location)       return True  def down(location):   if location[1] == 4:     return False   else:     new_location = [location[0],location[1]+1]     if new_location in route_history:       return False     elif source[new_location[0]][new_location[1]] == 1:       return False     else:       route_stack.append(new_location)       route_history.append(new_location)       return True  def left(location):   if location[0] == 0:     return False   else:     new_location = [location[0]-1,location[1]]     if new_location in route_history:       return False     elif source[new_location[0]][new_location[1]] == 1:       return False     else:       route_stack.append(new_location)       route_history.append(new_location)       return True  def right(location):   if location[0] == 4:     return False   else:     new_location = [location[0]+1,location[1]]     if new_location in route_history:       return False     elif source[new_location[0]][new_location[1]] == 1:       return False     else:       route_stack.append(new_location)       route_history.append(new_location)       return True lo = [0,0] while route_stack[-1] != [4,4]:   if up(lo):     lo = route_stack[-1]     continue   if down(lo):     lo = route_stack[-1]     continue   if left(lo):     lo = route_stack[-1]     continue   if right(lo):     lo = route_stack[-1]     continue   route_stack.pop()   lo = route_stack[-1] print route_stack