1954 - Pku3764 The xor-longest Path

给定一棵n个点的带权树，求树上最长的异或和路径

The input contains several test cases. The first line of each test case contains an integer n(1<=n<=100000), The following n-1 lines each contains three integers u(0 <= u < n),v(0 <= v < n),w(0 <= w < 2^31), which means there is an edge between node u and v of length w.

For each test case output the xor-length of the xor-longest path.

The xor-longest path is 1->2->3, which has length 7 (=3 ⊕ 4) 注意：结点下标从1开始到N....