Query on a tree

  There are some queries on a tree which has n nodes. Every query is described as two integers (X, Y).For each query, you should find the maximum weight of the edges in set E, which satisfies the following two conditions.
1) The edge must on the path from node X to node 1.
2) The edge’s weight should be lower or equal to Y.
  Now give you the tree and queries. Can you find out the answer for each query?

  The first line of the input is an integer T, indicating the number of test cases. For each case, the first line contains an integer n indicates the number of nodes in the tree. Then n-1 lines follows, each line contains three integers X, Y, W indicate an edge between node X and node Y whose value is W. Then one line has one integer Q indicates the number of queries. In the next Q lines, each line contains two integers X and Y as said above.

  For each test case, you should output Q lines. If no edge satisfy the conditions described above，just output “-1” for this query. Otherwise output the answer for this query.

1
3
1 2 7
2 3 5
4
3 10
3 7
3 6
3 4

7
7
5
-1

2<=n<=10^5
2<=Q<=10^5
1<=W,Y<=10^9
The data is guaranteed that your program will overflow if you use recursion.

Edward_mj

ACM-DIY Group Contest 2011 Spring