9549: ABC239 —— E - Subtree K-th Max
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Description
We have a rooted tree with $N$ vertices. The vertices are numbered $1$ through $N$, and the root is Vertex $1$.
The $i$-th edge connects Vertices $A_i$ and $B_i$.
Vertex $i$ has an integer $X_i$ written on it.
You are given $Q$ queries. For the $i$-th query, given a pair of integers $(V_i,K_i)$, answer the following question.
- Question: among the integers written on the vertices in the subtree rooted at Vertex $V_i$, find the $K_i$-th largest value.
The $i$-th edge connects Vertices $A_i$ and $B_i$.
Vertex $i$ has an integer $X_i$ written on it.
You are given $Q$ queries. For the $i$-th query, given a pair of integers $(V_i,K_i)$, answer the following question.
- Question: among the integers written on the vertices in the subtree rooted at Vertex $V_i$, find the $K_i$-th largest value.
Input
Input is given from Standard Input in the following format:
```
$N$ $Q$
$X_1$ $\ldots$ $X_N$
$A_1$ $B_1$
$\vdots$
$A_{N-1}$ $B_{N-1}$
$V_1$ $K_1$
$\vdots$
$V_Q$ $K_Q$
```
```
$N$ $Q$
$X_1$ $\ldots$ $X_N$
$A_1$ $B_1$
$\vdots$
$A_{N-1}$ $B_{N-1}$
$V_1$ $K_1$
$\vdots$
$V_Q$ $K_Q$
```
Output
Print $Q$ lines. The $i$-th line should contain the response to the $i$-th query.
Constraints
- $2 \leq N \leq 10^5$
- $0\leq X_i\leq 10^9$
- $1\leq A_i,B_i\leq N$
- $1\leq Q \leq 10^5$
- $1\leq V_i\leq N$
- $1\leq K_i\leq 20$
- The given graph is a tree.
- The subtree rooted at Vertex $V_i$ has $K_i$ or more vertices.
- All values in input are integers.
- $0\leq X_i\leq 10^9$
- $1\leq A_i,B_i\leq N$
- $1\leq Q \leq 10^5$
- $1\leq V_i\leq N$
- $1\leq K_i\leq 20$
- The given graph is a tree.
- The subtree rooted at Vertex $V_i$ has $K_i$ or more vertices.
- All values in input are integers.
Sample 1 Input
5 2
1 2 3 4 5
1 4
2 1
2 5
3 2
1 2
2 1
Sample 1 Output
4
5
The tree given in this input is shown below.
For the 1-st query, the vertices in the subtree rooted at Vertex 1 are Vertices 1,2,3,4, and 5, so print the 2-nd largest value of the numbers written on these vertices, 4.
For the 2-nd query, the vertices in the subtree rooted at Vertex 2 are Vertices 2,3, and 5, so print the 1-st largest value of the numbers written on these vertices, 5.
Sample 2 Input
6 2
10 10 10 9 8 8
1 4
2 1
2 5
3 2
6 4
1 4
2 2
Sample 2 Output
9
10
Sample 3 Input
4 4
1 10 100 1000
1 2
2 3
3 4
1 4
2 3
3 2
4 1
Sample 3 Output
1
10
100
1000