Codeforces Round 778 (Div. 1 + Div. 2, based on Technocup 2022 Final Round)
G
Snowy Mountain
Codeforces
2900
原题
← FH →
翻译中…

There are $n$ locations on a snowy mountain range (numbered from $1$ to $n$), connected by $n-1$ trails in the shape of a tree. Each trail has length $1$. Some of the locations are base lodges. The height $h_i$ of each location is equal to the distance to the nearest base lodge (a base lodge has height $0$).

翻译中…

There is a skier at each location, each skier has initial kinetic energy $0$. Each skier wants to ski along as many trails as possible. Suppose that the skier is skiing along a trail from location $i$ to $j$. Skiers are not allowed to ski uphill (i.e., if $h_i \lt h_j$). It costs one unit of kinetic energy to ski along flat ground (i.e., if $h_i = h_j$), and a skier gains one unit of kinetic energy by skiing downhill (i.e., if $h_i \gt h_j$). For each location, compute the length of the longest sequence of trails that the skier starting at that location can ski along without their kinetic energy ever becoming negative. Skiers are allowed to visit the same location or trail multiple times.

翻译中…

Input

翻译中…

The first line contains a single integer $n$ ($2 \le n \le 2 \cdot 10^5$).

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The second line contains $n$ integers $l_1, l_2, \ldots, l_n$ ($0 \le l_i \le 1$). If $l_i = 1$, location $i$ is a base lodge; if $l_i = 0$, location $i$ is not a base lodge. It is guaranteed that there is at least $1$ base lodge.

翻译中…

Each of the next $n-1$ lines contains two integers $u, v$ ($1 \leq u, v \leq n$, $u \neq v$), meaning that there is a trail that connects the locations $u$ and $v$. It is guaranteed that the given trails form a tree.

翻译中…

Output

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Print $n$ integers: the $i$-th integer is equal to the length of the longest sequence of trails that the skier starting at location $i$ can ski along without their kinetic energy ever becoming negative.

翻译中…

Note

翻译中…

In the first test, $h = [0, 0, 1, 1, 2, 3]$. The skier starting from $6$ can ski along at most $5$ trails, in the path $6 \rightarrow 5 \rightarrow 4 \rightarrow 3 \rightarrow 4 \rightarrow 2$ (notice that a skier can ski multiple times along the same trail and can visit more than once the same location):

翻译中…
  • at the location $6$, the kinetic energy is $0$;
  • at the location $5$, the kinetic energy increases by $1$ (because $h_5 \lt h_6$), so it becomes $1$;
  • at the location $4$, the kinetic energy increases by $1$ (because $h_4 \lt h_5$), so it becomes $2$;
  • at the location $3$, the kinetic energy decreases by $1$ (because $h_3 = h_4$), so it becomes $1$;
  • at the location $4$, the kinetic energy decreases by $1$ (because $h_4 = h_3$), so it becomes $0$;
  • at the location $2$, the kinetic energy increases by $1$ (because $h_2 \lt h_4$), so it becomes $1$.
翻译中…

There isn't any sequence of trails of length greater than $5$ such that the kinetic energy is always non-negative.

翻译中…

Moreover,

翻译中…
  • the optimal path for the skier starting from $1$ is $1$ (no trails);
  • the optimal path for the skier starting from $2$ is $2$ (no trails);
  • the optimal path for the skier starting from $3$ is $3 \rightarrow 1$;
  • the optimal path for the skier starting from $4$ is $4 \rightarrow 2$;
  • the optimal path for the skier starting from $5$ is $5 \rightarrow 4 \rightarrow 3 \rightarrow 1$.
翻译中…

In the second test, $h = [3, 2, 2, 1, 1, 1, 0, 0, 0]$. The skier starting from $1$ can ski along at most $5$ trails, in the path $1 \rightarrow 3 \rightarrow 2 \rightarrow 5 \rightarrow 4 \rightarrow 7$.

翻译中…
  • at the location $1$, the kinetic energy is $0$;
  • at the location $3$, the kinetic energy increases by $1$ (because $h_3 \lt h_1$), so it becomes $1$;
  • at the location $2$, the kinetic energy decreases by $1$ (because $h_2 = h_3$), so it becomes $0$;
  • at the location $5$, the kinetic energy increases by $1$ (because $h_5 \lt h_2$), so it becomes $1$;
  • at the location $4$, the kinetic energy decreases by $1$ (because $h_4 = h_5$), so it becomes $0$;
  • at the location $7$, the kinetic energy increases by $1$ (because $h_7 \lt h_4$), so it becomes $1$.
翻译中…

There isn't any sequence of trails of length greater than $5$ such that the kinetic energy is always non-negative.

翻译中…

In the third test, for the skier starting from vertex $1$, the optimal path is $1 \rightarrow 2 \rightarrow 5 \rightarrow 4 \rightarrow 3 \rightarrow 6 \rightarrow 11 \rightarrow 10 \rightarrow 11$.

翻译中…

Here are pictures of the first, second, and third test, with the base lodges shown in red:

翻译中…

image

翻译中…

样例

Input #1
6
1 1 0 0 0 0
1 3
2 4
3 4
4 5
5 6
Output #1
0 0 1 1 3 5
InputCopy OutputCopy
Input #2
9
0 0 0 0 0 0 1 1 1
1 3
2 3
2 5
3 6
4 5
4 7
5 8
6 9
Output #2
5 3 2 1 1 1 0 0 0
InputCopy OutputCopy
Input #3
14
0 0 0 0 0 0 0 0 0 1 1 1 1 1
1 2
2 5
3 4
4 5
3 6
4 8
5 9
7 8
6 11
7 12
8 13
9 14
10 11
Output #3
8 5 4 3 2 2 1 1 1 0 0 0 0 0
InputCopy OutputCopy
Input #4
20
0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 0 1 0 1
17 3
11 12
6 10
18 19
8 14
16 20
5 3
2 11
7 10
2 15
8 3
3 15
9 16
7 13
16 1
19 2
2 16
6 1
4 17
Output #4
2 2 1 5 3 4 8 1 2 6 4 6 10 0 0 0 3 0 1 0
InputCopy OutputCopy
题目信息
题号
1654G
时间限制
5 s
内存限制
1024 MB
标签
数据结构
DFS 及类似
图论
贪心
最短路
树

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