CF1566E.Buds Re-hanging

普及/提高-

通过率:0%

AC君温馨提醒

该题目为【codeforces】题库的题目,您提交的代码将被提交至codeforces进行远程评测,并由ACGO抓取测评结果后进行展示。由于远程测评的测评机由其他平台提供,我们无法保证该服务的稳定性,若提交后无反应,请等待一段时间后再进行重试。

题目描述

A tree is a connected graph without cycles. A rooted tree has a special vertex called the root. The parent of a vertex vv (different from root) is the previous to vv vertex on the shortest path from the root to the vertex vv . Children of the vertex vv are all vertices for which vv is the parent.

A vertex is a leaf if it has no children. We call a vertex a bud, if the following three conditions are satisfied:

  • it is not a root,
  • it has at least one child, and
  • all its children are leaves.

You are given a rooted tree with nn vertices. The vertex 11 is the root. In one operation you can choose any bud with all its children (they are leaves) and re-hang them to any other vertex of the tree. By doing that you delete the edge connecting the bud and its parent and add an edge between the bud and the chosen vertex of the tree. The chosen vertex cannot be the bud itself or any of its children. All children of the bud stay connected to the bud.

What is the minimum number of leaves it is possible to get if you can make any number of the above-mentioned operations (possibly zero)?

输入格式

The input consists of multiple test cases. The first line contains a single integer tt ( 1t1041 \le t \le 10^4 ) — the number of test cases. Description of the test cases follows.

The first line of each test case contains a single integer nn ( 2n21052 \le n \le 2 \cdot 10^5 ) — the number of the vertices in the given tree.

Each of the next n1n-1 lines contains two integers uu and vv ( 1u,vn1 \le u, v \le n , uvu \neq v ) meaning that there is an edge between vertices uu and vv in the tree.

It is guaranteed that the given graph is a tree.

It is guaranteed that the sum of nn over all test cases doesn't exceed 21052 \cdot 10^5 .

输出格式

For each test case print a single integer — the minimal number of leaves that is possible to get after some operations.

输入输出样例

  • 输入#1

    5
    7
    1 2
    1 3
    1 4
    2 5
    2 6
    4 7
    6
    1 2
    1 3
    2 4
    2 5
    3 6
    2
    1 2
    7
    7 3
    1 5
    1 3
    4 6
    4 7
    2 1
    6
    2 1
    2 3
    4 5
    3 4
    3 6

    输出#1

    2
    2
    1
    2
    1

说明/提示

In the first test case the tree looks as follows:

Firstly you can choose a bud vertex 44 and re-hang it to vertex 33 . After that you can choose a bud vertex 22 and re-hang it to vertex 77 . As a result, you will have the following tree with 22 leaves:

It can be proved that it is the minimal number of leaves possible to get.

In the second test case the tree looks as follows:

You can choose a bud vertex 33 and re-hang it to vertex 55 . As a result, you will have the following tree with 22 leaves:

It can be proved that it is the minimal number of leaves possible to get.

首页