摘要：星球大战 有一棵树。每次可以攻击树上的某棵子树，然后这棵子树上的每条边有$\frac{1}{2}$的概率消失。定义 若攻击以x为根的子树，深度ht(x)为x子树剩余点(与x连通)的最大深度。共q次操作，两种： 1 x.新建一个节点，其父节点为x。2 x.询问若攻击以x为根的子树，x子树的期望深度。 阅读全文

摘要：Lights inside 3D Grid You are given a 3D grid, which has dimensions X, Y and Z. Each of the X x Y x Z cells contains a light. Initially all lights are 阅读全文

摘要：Discovering Gold You are in a cave, a long cave! The cave can be represented by a 1 x N grid. Each cell of the cave can contain any amount of gold. In 阅读全文

摘要：A Dangerous Maze You are in a maze; seeing n doors in front of you in beginning. You can choose any door you like. The probability for choosing a door 阅读全文

摘要：POJ3071 Description Consider a single-elimination football tournament involving $2n$ teams, denoted $1, 2, …, 2n$. In each round of the tournament, al 阅读全文