题目描述
Problem Description
You are given a $\texttt{01}$ sequence of length $n$ with indices $1, 2, \dots, n$. Initially, each character represents a string of length $1$. In a concatenation operation, you need to select two strings $a$ and $b$, delete them, and replace them with the string $ab$, which is formed by writing all characters of $a$ followed by all characters of $b$.
These $n$ initial strings need to be concatenated into one string using $n-1$ concatenation operations. The $i$-th operation is described by a pair of indices $(a_i, b_i)$, indicating that the strings containing the characters at indices $a_i$ and $b_i$ are to be concatenated. It is guaranteed that the characters at indices $a_i$ and $b_i$ are not in the same string.
The palindromic value of a string $w$ is defined as the number of distinct palindromic substrings in $w$. A palindromic string is one that reads the same forwards and backwards. A substring is defined as a string that can be obtained by deleting one or more characters from the beginning and/or end of the original string.
For each concatenation operation, output the palindromic value of the resulting string.
Input Format
The first line contains an integer $n$, the number of characters.
The second line contains a $\texttt{01}$ string of length $n$, representing the initial strings.
The next $n-1$ lines each contain two integers $a_i$ and $b_i$, describing the $i$-th concatenation operation.
Output Format
Output $n-1$ lines, each representing the palindromic value of the string obtained after each concatenation operation.
Sample Input and Output
Input Sample #1
3
010
1 2
2 3
Output Sample #1
2
3
Input Sample #2
5
00111
4 1
1 5
2 1
3 1
Output Sample #2
2
3
4
5
Input Sample #3
8
10010000
7 5
4 2
3 6
1 3
6 8
5 3
1 2
Output Sample #3
2
2
2
3
4
6
8
Notes
Sample Explanation 3:
The strings created after each concatenation are: $\tt 00, 10, 00, 100, 1000, 001000$ and $\tt 00100010$.
Their respective palindromic values are given in the sample output. For example, the palindromic value of $\tt 00100010$ is $8$ because the string contains $8$ palindromic substrings: $\tt 0, 00, 000, 10001, 0100010, 1010$ and $00100$.
Data Range:
For $9\%$ of the data: $1 \le n \le 100$
For $18\%$ of the data: $1 \le n \le 1000$
For $27\%$ of the data: $a_i = 1, b_i = i + 1$
For $100\%$ of the data: $1 \le n \le 10^5$, $1 \le a_i, b_i \le n$
This problem has the same scoring as COCI 2021-2022#6, with a maximum score of $110$ points.
输入格式
见题面 Input 部分
输出格式
见题面 Output 部分