1943.Bear and Tree Jumps

Time Limit: 1s Memory Limit: 256MB

A tree is an undirected connected graph without cycles. The distance between two vertices is the number of edges in a simple path between them.Limak is a little polar bear. He lives in a tree that consists of n vertices, numbered 1 through n.Limak recently learned how to jump. He can jump from a vertex to any vertex within distance at most k.For a pair of vertices (s,t) we define f(s,t) as the minimum number of jumps Limak needs to get from s to t. Your task is to find the sum of f(s,t) over all pairs of vertices (s,t) such that s \lt t.

Input Format(From the terminal/stdin)

Input The first line of the input contains two integers n and k (2 \le n \le 200000, 1 \le k \le 5)- the number of vertices in the tree and the maximum allowed jump distance respectively.The next n-1 lines describe edges in the tree. The i-th of those lines contains two integers ai and bi (1 \le ai,bi \le n)- the indices on vertices connected with i-th edge.It's guaranteed that the given edges form a tree.

Output Format(To the terminal/stdout)

Output Print one integer, denoting the sum of f(s,t) over all pairs of vertices (s,t) such that s \lt t.

Sample Input 1

Copy
6 2
1 2
1 3
2 4
2 5
4 6
 · \n
 · \n
 · \n
 · \n
 · \n
 · \n

Sample Output 1

Copy
20
  \n

Sample Input 2

Copy
13 3
1 2
3 2
4 2
5 2
3 6
10 6
6 7
6 13
5 8
5 9
9 11
11 12
  · \n
 · \n
 · \n
 · \n
 · \n
 · \n
  · \n
 · \n
 ·  \n
 · \n
 · \n
 ·  \n
  ·  \n

Sample Output 2

Copy
114
   \n

Sample Input 3

Copy
3 5
2 1
3 1
 · \n
 · \n
 · \n

Sample Output 3

Copy
3
 \n

Hints

In the first sample, the given tree has 6 vertices and it's displayed on the drawing below. Limak can jump to any vertex within distance at most 2. For example, from the vertex 5 he can jump to any of vertices: 1, 2 and 4 (well, he can also jump to the vertex 5 itself). 1943_1.png There are 1943_2.png pairs of vertices (s,t) such that s \lt t. For 5 of those pairs Limak would need two jumps: (1,6),(3,4),(3,5),(3,6),(5,6). For other 10 pairs one jump is enough. So, the answer is 5 \cdot 2+10 \cdot 1=20.In the third sample, Limak can jump between every two vertices directly. There are 3 pairs of vertices (s \lt t), so the answer is 3 \cdot 1=3.

Submit

请先 登录

© 2025 FAQs