A954 | Cow Land--Gold

Cow Land is a special amusement park for cows, where they roam around, eat
delicious grass, and visit different cow attractions (the roller cowster is
particularly popular).
There are a total of $N$ different attractions ($2 \leq N \leq 10^5$). Certain
pairs of attractions are connected by pathways, $N-1$ in total, in such a way
that there is a unique route consisting of various pathways between any two
attractions. Each attraction $i$ has an integer enjoyment value $e_i$, which
can change over the course of a day, since some attractions are more appealing
in the morning and others later in the afternoon.
A cow that travels from attraction $i$ to attraction $j$ gets to experience
all the attractions on the route from $i$ to $j$. Curiously, the total
enjoyment value of this entire route is given by the bitwise XOR of all the
enjoyment values along the route, including those of attractions $i$ and $j$.
Please help the cows determine the enjoyment values of the routes they plan to
use during their next trip to Cow Land.

The first line of input contains $N$ and a number of queries $Q$ ($1 \leq Q
\leq 10^5$). The next line contains $e_1 \ldots e_N$ ($0 \leq e_i \leq 10^9$).
The next $N-1$ lines each describe a pathway in terms of two integer
attraction IDs $a$ and $b$ (both in the range $1 \ldots N$). Finally, the last
$Q$ lines each describe either an update to one of the $e_i$ values or a query
for the enjoyment of a route. A line of the form "1 $i$ $v$" indicates that
$e_i$ should be updated to value $v$, and a line of the form "2 $i$ $j$" is a
query for the enjoyment of the route connecting attractions $i$ and $j$.
In test data worth at most 50% of points, there will be no changes to the
values of the attractions.

For each query of the form "2 $i$ $j$", print on a single line the enjoyment
of the route from $i$ to $j$.