Codeforces Round 897 (Div. 2)
B
XOR Palindromes
Codeforces
1100
原题
← AC →
翻译中…

You are given a binary string $s$ of length $n$ (a string that consists only of $0$ and $1$). A number $x$ is good if there exists a binary string $l$ of length $n$, containing $x$ ones, such that if each symbol $s_i$ is replaced by $s_i \oplus l_i$ (where $\oplus$ denotes the bitwise XOR operation), then the string $s$ becomes a palindrome.

翻译中…

You need to output a binary string $t$ of length $n+1$, where $t_i$ ($0 \leq i \leq n$) is equal to $1$ if number $i$ is good, and $0$ otherwise.

翻译中…

A palindrome is a string that reads the same from left to right as from right to left. For example, 01010, 1111, 0110 are palindromes.

翻译中…

Input

翻译中…

Each test contains multiple test cases. The first line contains the number of test cases $t$ ($1 \le t \le 10^5$). The description of the test cases follows.

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The first line of each test case contains a single integer $n$ ($1 \le n \le 10^5$).

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The second line of each test case contains a binary string $s$ of length $n$.

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It is guaranteed that the sum of $n$ over all test cases does not exceed $10^5$.

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Output

翻译中…

For each test case, output a single line containing a binary string $t$ of length $n+1$ - the answer to the problem.

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Note

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Consider the first example.

翻译中…
  • $t_2 = 1$ because we can choose $l = $ 010100, then the string $s$ becomes 111111, which is a palindrome.
  • $t_4 = 1$ because we can choose $l = $ 101011.
  • It can be shown that for all other $i$, there is no answer, so the remaining symbols are $0$.
翻译中…

样例

Input #1
5
6
101011
5
00000
9
100100011
3
100
1
1
Output #1
0010100
111111
0011111100
0110
11
InputCopy OutputCopy
题目信息
题号
1867B
时间限制
1 s
内存限制
256 MB
标签
位运算
构造
字符串

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