Code | 野人与传教士

'''
问题描述：三个野人，三个传教士，一艘船，船上至多有两人，在一起的野人数不能超过传教士，否则传教士被吃。
状态=[传教士数，野人数，船是否在本岸] 
动作=[传教士上船人数，野人上船人数]

变量说明：
*state_route:[[state],[action1]，[action2]] 用以描述当前state，是经过怎样的动作序列得到。
*state_table: [state_route, stateroute...] 未探索的状态及路径列表
*searched_table:[state,state...] 已探索的状态列表

'''

def state_transfer(state_route, action):
    route = state_route.copy()
    state = route[0]
    new_state = [0, 0, 0]

    if state[2] == 1:
        if state[0] < action[0] or state[1] < action[1]:
            return False
        else:
            new_state[0] = state[0]-action[0]
            new_state[1] = state[1]-action[1]
            new_state[2] = 1-state[2]
    else:
        if 3-state[0] < action[0] or 3-state[1] < action[1]:
            return False
        else:
            new_state[0] = state[0]+action[0]
            new_state[1] = state[1]+action[1]
            new_state[2] = 1-state[2]

    if new_state[0] < new_state[1] and new_state[0] != 0:
        return False
    if 3-new_state[0] < 3-new_state[1] and 3-new_state[0] != 0:
        return False
    route[0] = new_state
    route.append(action)
    return route


def main():
    state_table = []
    state_route = []
    target = [0,0,0]
    state_init = [3, 3, 1]
    state_route.append(state_init.copy())
    state_table.append(state_route.copy())
    searched_table = []
    action = [[0,1],[1,0],[0,2],[2,0],[1,1]]

    while state_table != []:
        if state_table[0][0] not in searched_table:
            for i in range(5):
                state_route = state_transfer(state_table[0], action[i])
                if state_route is False:
                    continue
                if state_route[0] == target:
                    print(state_route)
                    break
                state_table.append(state_route)
            searched_table.append(state_table[0][0])
        state_table.pop(0)


if __name__ == "__main__":
    main()