yanghong的博客

HDU-3507-打印文章[Task][Task]:Zero has an old printer that doesn’t work well sometimes. As it is antique, he still like to use it to print articles. But it is too old to work for a long time and it will ce

树分治:树分治是一种解决树上路径问题的一种神奇方法. 它可以把复杂度为 O(nklogn...nk+1)O(n^klogn...n^{k+1}) 问题变为最高复杂度为O(nklogn)O(n^klogn)的问题(当然不是随便乱搞的)假如,一颗树长得很正常,那么它的深度大约为lognlogn. 但是,如果一棵树长得很畸形(比如一条链),那深度就是n了.如果对于每一个子树,可以随便选择根节点的话,那就