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r 个无区别的小球分别放入 n 个不同的盒子中,每个盒子所放球数不加限制,其放法总数为:G_(n+r-1)~r.在解一些组合问题时经常用到这一结论,我们可以把这个结论看成一个模型,即“球·盒子模型”,利用这个模型我们可以很方便地解决一些组合问题.首先证明这个结论.考察 n+1个1和个 r
The r indiscriminate balls are put into n different boxes. The number of balls placed in each box is not limited. The total number of shots is: G_(n+r-1)~r. We often use this conclusion, we can see this conclusion as a model, that is, “ball box model”, using this model we can easily solve some combination problems. First prove this conclusion. Check n+1 1 And r