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Loaded dice with a uniformly distributed sum
Show that if a sum of two independent integer random variables is uniform on its support, then each summand is uniform on its own support.
比较改动
选两个分支看看改了什么，再发起 PR 把工作带过去。
选两个不同的分支
PR 可以从任何一个分支合入任何另一个分支。