6826.Distance Queries

Time Limit: 1s Memory Limit: 512MB

You are given a tree consisting of $n$ nodes.

Your task is to process $q$ queries of the form: what is the distance between nodes $a$ and $b$ ?

Input Format(From the terminal/stdin)

The first input line contains two integers $n$ and $q$ : the number of nodes and queries. The nodes are numbered $1,2,\ldots,n$ .

Then there are $n-1$ lines describing the edges. Each line contains two integers $a$ and $b$ : there is an edge between nodes $a$ and $b$ .

Finally, there are $q$ lines describing the queries. Each line contains two integer $a$ and $b$ : what is the distance between nodes $a$ and $b$ ?

  • $1 \le n, q \le 2 \cdot 10^5$
  • $1 \le a,b \le n$

Output Format(To the terminal/stdout)

Print $q$ integers: the answer to each query.

Sample Input

Copy
5 3
1 2
1 3
3 4
3 5
1 3
2 5
1 4
 · \n
 · \n
 · \n
 · \n
 · \n
 · \n
 · \n
 · \n

Sample Output

Copy
1
3
2
 \n
 \n
 \n
Source: CSES, Tree Algorithms, 1135

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