CF1512C.A-B Palindrome

You are given a string $s$ consisting of the characters '0', '1', and '?'. You need to replace all the characters with '?' in the string $s$ by '0' or '1' so that the string becomes a palindrome and has exactly $a$ characters '0' and exactly $b$ characters '1'. Note that each of the characters '?' is replaced independently from the others.

A string $t$ of length $n$ is called a palindrome if the equality $t[i] = t[n-i+1]$ is true for all $i$ ($1 \le i \le n$).

For example, if $s=$"01?????0", $a=4$ and $b=4$, then you can replace the characters '?' in the following ways:

• "01011010";
• "01100110".

For the given string $s$ and the numbers $a$ and $b$, replace all the characters with '?' in the string $s$ by '0' or '1' so that the string becomes a palindrome and has exactly $a$ characters '0' and exactly $b$ characters '1'.

给你一个由字符 '0'、'1' 和 '?' 组成的字符串 $s$。你需要将字符串 $s$ 中所有 '?' 字符分别独立地替换为 '0' 或 '1'，使得最终字符串成为一个回文串，且恰好包含 $a$ 个 '0' 字符和 $b$ 个 '1' 字符。

长度为 $n$ 的字符串 $t$ 被称为回文串，当且仅当对所有 $i$（$1 \le i \le n$）均满足 $t[i] = t[n-i+1]$。

例如，若 $s =$ "01?????0"，$a = 4$ 且 $b = 4$，则你可以按如下方式替换 '?' 字符：

• "01011010"；
• "01100110"。

对于给定的字符串 $s$ 以及整数 $a$ 和 $b$，请将字符串 $s$ 中所有 '?' 字符替换为 '0' 或 '1'，使得最终字符串是一个回文串，且恰好包含 $a$ 个 '0' 和 $b$ 个 '1'。

The first line contains a single integer $t$ ($1 \le t \le 10^4$). Then $t$ test cases follow.

The first line of each test case contains two integers $a$ and $b$ ($0 \le a, b \le 2 \cdot 10^5$, $a + b \ge 1$).

The second line of each test case contains the string $s$ of length $a+b$, consisting of the characters '0', '1', and '?'.

It is guaranteed that the sum of the string lengths of $s$ over all test cases does not exceed $2 \cdot 10^5$.

第一行包含一个整数 $t$（$1 \le t \le 10^4$）。随后是 $t$ 组测试数据。

每组测试数据的第一行包含两个整数 $a$ 和 $b$（$0 \le a, b \le 2 \cdot 10^5$，且 $a + b \ge 1$）。

每组测试数据的第二行包含一个长度为 $a+b$ 的字符串 $s$，该字符串仅由字符 '0'、'1' 和 '?' 组成。

保证所有测试数据中字符串 $s$ 的总长度不超过 $2 \cdot 10^5$。

For each test case, output:

• "-1", if you can't replace all the characters '?' in the string $s$ by '0' or '1' so that the string becomes a palindrome and that it contains exactly $a$ characters '0' and exactly $b$ characters '1';
• the string that is obtained as a result of the replacement, otherwise.

If there are several suitable ways to replace characters, you can output any.

对于每个测试用例，输出：

• “-1”，如果你无法将字符串 $s$ 中的所有字符 '?' 替换为 '0' 或 '1'，使得该字符串成为一个回文串，且恰好包含 $a$ 个字符 '0' 和恰好 $b$ 个字符 '1'；
• 否则，输出替换后得到的字符串。

如果存在多种合适的替换方式，你可以输出任意一种。