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HDU5102(树的前k路径+队列)

The K-th Distance

Time Limit: 8000/4000 MS (Java/Others)    Memory Limit: 65536/65536 K (Java/Others)
Total Submission(s): 332    Accepted Submission(s): 90


Problem Description
Given a tree, which has n node in total. Define the distance between two node u and v is the number of edge on their unique route. So we can have n(n-1)/2 numbers for all the distance, then sort the numbers in ascending order. The task is to output the sum of the first K numbers.
 

Input
There are several cases, first is the number of cases T. (There are most twenty cases).
For each case, the first line contain two integer n and K (2n100000,0Kmin(n(n?1)/2,106) ). In following there are n-1 lines. Each line has two integer u , v. indicate that there is an edge between node u and v.
 

Output
For each case output the answer.
 

Sample Input
2 3 3 1 2 2 3 5 7 1 2 1 3 2 4 2 5
 

Sample Output
4 10
 

Source
BestCoder Round #17

题意:给出一棵树,边权为1,求前k长的路径和

思路:用一个队列维护即可,先将所有边入队,然后不停的用边的一个端点向外扩张,每扩张一次,路径长度就+1

            这样求出前k个即可

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HDU5102(树的前k路径+队列)