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“不相邻”问题是排列组合中大家所熟悉的一种常见类型,此类问题咋看起来很简单、方法也很明确———插空法,但对于其中一些问题,经过“华丽”的变身后让人总感到模棱两可、琢磨不定.一、基本模型例1将3个白球、5个红球排成一排,其中3个白球互不相邻①若同色球之间加以区分,共有多少种不同的排法?②若同色球之间不加以区分,共有多少种不同的排法?
“Not adjacent ” problem is a familiar type of arrangement familiar to everyone, such a problem seems very simple, the method is also very clear - plug-in method, but for some of them, after “ Gorgeous ”people always feel ambiguous, pondering indefinite.First, the basic model example 1 will be 3 white balls, 5 red balls in a row, of which 3 white balls are not adjacent to each other ① if the same color ball to be How many different ways to differentiate? How many different ways to distinguish between chromospheres?