COCI '21 Contest 6 #4 Palindromi
View as PDFYou are given a sequence of  characters, 
0 or 1, indexed by numbers . Initially, every character
represents a string of length one. During a concatenation, two words, 
 and 
, are chosen, deleted, and
replaced by the string 
 such that the characters of 
 are written after the characters of 
.
The  initial strings are concatenated to one final string using a sequence of 
 concatenations. The 
of those concatenation is described by a pair of indices 
, which denotes that the string containing
 character and the string containing 
 character are to be concatenated. It is guaranteed that
characters with indices 
 and 
 are not in the same string.
Palindromic value of some string  is defined as the total number of unique substrings of 
 which are
palindromes. We define palindromes as strings that are the same when read left to right and right to
left. A substring of a string is defined as a string obtained by erasing zero or more characters from the
beginning and/or ending of the string.
For every concatenation, print the palindromic value of the resulting string.
Input Specification
The first line contains an integer  
, number of characters.
In the second line, there is a string of  characters 
0 and 1 which represent the initial strings.
The  of following 
 lines contains two integers 
 
 representing the 
concatenation.
Output Specification
Print  lines, the palindromic values of words obtained after each concatenation.
Constraints
| Subtask | Points | Constraints | 
|---|---|---|
| No additional constraints. | 
Sample Input 1
3
010
1 2
2 3
Sample Output 1
2
3
Sample Input 2
5
00111
4 1
1 5
2 1
3 1
Sample Output 2
2
3
4
5
Sample Input 3
8
10010000
7 5
4 2
3 6
1 3
6 8
5 3
1 2
Sample Output 3
2
2
2
3
4
6
8
Explanation for Sample Output 3
Newly created strings after every concatenation are: 00, 10, 00, 100, 1000, 001000, and 00100010. Their
respective palindromic values are given in the example output. E.g., the palindromic value of 00100010
is  because the string contains 
 palindromic substrings: 
0, 00, 000, 10001, 0100010, 1, 010, 00100.
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