用python实现：学生挑选倒垃圾人选的策略为：黑白配和石头剪刀布猜拳选出。遵循以下规则： 工、在人数多于4个人的时候，使用黑白配猜拳方式，即每人每次猜拳时出手心（白） 和手背（黑，两种方式，每次猜拳后，人数少的一方不参与下一轮猜拳。人数多的一方继续进行。 二、在猜拳人数为4人的时候，随机两两进行石头剪刀布的猜拳，如果有2个垃圾桶需要清理，则输的两个人一人一个去倒垃圾，如果只有1个垃圾桶需要清理，则第一轮输的两个人继续进行石头剪刀布的猜拳，最后输的那一个人去清理垃圾桶。 3、在猜拳人数为了人的时候，继续进行黑白配的猜拳，剩下2 人后，如果有2个垃圾桶需要清理，则两个人一人一个去倒垃圾，如果只有1个垃圾桶需要清理，则剩下两个人继续进行石头剪刀布的猜拳，最后输的那一个人去清理垃圾桶。

这里是一个用Python实现上述问题的示例代码：

import random

# 定义石头剪刀布的胜负规则
def judge_gesture(gesture1, gesture2):
    if gesture1 == gesture2:
        return 0
    elif gesture1 == 'rock' and gesture2 == 'scissors' or \
         gesture1 == 'scissors' and gesture2 == 'paper' or \
         gesture1 == 'paper' and gesture2 == 'rock':
        return 1
    else:
        return -1

# 定义黑白配猜拳的胜负规则
def judge_bw_gesture(gesture1, gesture2):
    if gesture1 == gesture2:
        return 0
    elif gesture1 == 'black':  # 手背胜
        return -1
    else:  # 手心胜
        return 1

# 定义清理垃圾桶的函数
def clean_rubbish(num):
    print('第%d个人去清理垃圾桶' % num)

# 定义黑白配猜拳的函数
def bw_gesture(players):
    print('黑白配猜拳开始!')
    black_count = 0  # 手背的人数
    white_count = 0  # 手心的人数
    for i in range(len(players)):
        if i % 2 == 0:
            gesture = 'black'  # 手背
            black_count += 1
        else:
            gesture = 'white'  # 手心
            white_count += 1
        print('第%d个人出%s' % (i+1, gesture))
        if i < len(players) - 1:
            # 判断胜负，输的人不参与下一轮猜拳
            j = i + 1 if judge_bw_gesture(gesture, players[i+1]) > 0 else i
            players.pop(j)
            if gesture == 'black':
                black_count -= 1
            else:
                white_count -= 1
    # 返回手背人数和手心人数
    return black_count, white_count

# 定义石头剪刀布猜拳的函数
def play_gesture(players, num_rubbish):
    print('石头剪刀布猜拳开始!')
    while len(players) > 2:
        win_count = [0] * len(players)  # 每个人的胜利次数
        for i in range(len(players)):
            for j in range(i+1, len(players)):
                gesture1 = random.choice(['rock', 'scissors', 'paper'])
                gesture2 = random.choice(['rock', 'scissors', 'paper'])
                result = judge_gesture(gesture1, gesture2)
                if result > 0:
                    win_count[i] += 1
                elif result < 0:
                    win_count[j] += 1
        # 找到胜利次数最多的两个人
        max1 = max(win_count)
        idx1 = win_count.index(max1)
        win_count[idx1] = -1
        max2 = max(win_count)
        idx2 = win_count.index(max2)
        # 判断输赢
        if num_rubbish == 2:
            if idx1 < idx2:
                clean_rubbish(idx1+1)
                clean_rubbish(idx2+1)
            else:
                clean_rubbish(idx2+1)
                clean_rubbish(idx1+1)
            players.pop(idx1)
            players.pop(idx2-1)
        elif num_rubbish == 1:
            while True:
                gesture1 = random.choice(['rock', 'scissors', 'paper'])
                gesture2 = random.choice(['rock', 'scissors', 'paper'])
                result = judge_gesture(gesture1, gesture2)
                if result != 0:
                    break
            if result > 0:
                clean_rubbish(idx1+1)
            else:
                clean_rubbish(idx2+1)
            players.pop(idx1 if result > 0 else idx2)
            players.pop(idx2-1 if result > 0 else idx1-1)
        else:
            print('清理垃圾桶出错!')
            break
    # 剩下两个人继续猜拳
    gesture1 = random.choice(['rock', 'scissors', 'paper'])
    gesture2 = random.choice(['rock', 'scissors', 'paper'])
    result = judge_gesture(gesture1, gesture2)
    if result > 0:
        clean_rubbish(players.index(max(players))+1)
    else:
        clean_rubbish(players.index(min(players))+1)

# 主程序
def main(num_players, num_rubbish):
    players = list(range(1, num_players+1))
    if num_players > 4:
        black_count, white_count = bw_gesture(players)
        if black_count > white_count:
            players = players[::2]
        else:
            players = players[1::2]
        play_gesture(players, num_rubbish)
    elif num_players == 4:
        play_gesture(players, num_rubbish)
    elif num_players == 3:
        black_count, white_count = bw_gesture(players)
        if black_count > white_count:
            clean_rubbish(players[::2][0])
        else:
            clean_rubbish(players[1::2][0])
    elif num_players == 2:
        gesture1 = random.choice(['rock', 'scissors', 'paper'])
        gesture2 = random.choice(['rock', 'scissors', 'paper'])
        result = judge_gesture(gesture1, gesture2)
        if result > 0:
            clean_rubbish(1)
        else:
            clean_rubbish(2)
    else:
        print('输入人数有误!')

# 调用主程序
main(6, 2)

这段代码实现了学生挑选倒垃圾人选的策略。可以根据需要调整输入参数，比如说可以改变参与猜拳的人数和垃圾桶的数量。