Shortest Path Problem?

题意翻译

见 [WC2011 最大XOR和路径](https://www.luogu.org/problemnew/show/P4151) --- 给定一张 $n$ 个点 $m$ 条边的无向图，一开始你在点 $1$，且价值为 $0$ 每次你可以选择一个相邻的点，然后走过去，并将价值异或上该边权 如果在点 $n$，你可以选择结束游戏 求一种方案，使得结束游戏后价值最小 $n,m \le 10^5$

题目描述

You are given an undirected graph with weighted edges. The length of some path between two vertices is the bitwise xor of weights of all edges belonging to this path (if some edge is traversed more than once, then it is included in bitwise xor the same number of times). You have to find the minimum length of path between vertex $ 1 $ and vertex $ n $ . Note that graph can contain multiple edges and loops. It is guaranteed that the graph is connected.

输入输出格式

输入格式

The first line contains two numbers $ n $ and $ m $ ( $ 1<=n<=100000 $ , $ n-1<=m<=100000 $ ) — the number of vertices and the number of edges, respectively. Then $ m $ lines follow, each line containing three integer numbers $ x $ , $ y $ and $ w $ ( $ 1<=x,y<=n $ , $ 0<=w<=10^{8} $ ). These numbers denote an edge that connects vertices $ x $ and $ y $ and has weight $ w $ .

输出格式

Print one number — the minimum length of path between vertices $ 1 $ and $ n $ .

输入输出样例

输入样例 #1

3 3
1 2 3
1 3 2
3 2 0

输出样例 #1

2

输入样例 #2

2 2
1 1 3
1 2 3

输出样例 #2

0