Erase and Append

AtCoder

IDarc207_e

Time2000ms

Memory256MB

Difficulty—

You are given strings $s$ and $t$ of length $N$ consisting of `0` and `1`. Determine whether it is possible to make $s$ match $t$ by performing the following operation at least $0$ and at most $N+1$ times, and if possible, show one such sequence of operations. Operation: Perform the following in order. 1. Choose integers $a$ and $b$ satisfying $1 \le a,b \le N$ and $|a-b|=1$ 2. Append the $a$\-th character from the beginning of $s$ to the end of $s$ 3. Remove the $b$\-th character from the beginning of $s$ and concatenate the remaining characters in their original order You are given $T$ test cases; find the answer for each of them. ## Constraints * $1 \le T \le 10^{5}$ * $2 \le N \le 2 \times 10^{5}$ * $s$ and $t$ are strings of length $N$ consisting of `0` and `1`. * The sum of $N$ over all test cases is at most $2 \times 10^{5}$. ## Input The input is given from Standard Input in the following format: $T$ $\text{case}_1$ $\text{case}_2$ $\vdots$ $\text{case}_T$ Each test case is given in the following format: $N$ $s$ $t$ [samples]

Samples

Input #1

Output #1

1
2 3
0
-1

In the first test case, $s$ is `00101` and $t$ is `00010`.

*   By choosing $2$ and $3$ as $a$ and $b$, appending the $2$\-nd character `0` to the end of $s$, and then removing the $3$\-rd character, we can make $s$ and $t$ match.
*   Note that the integers $a$ and $b$ chosen in the operation must satisfy $|a-b|=1$.

In the second test case, $s$ and $t$ can be made to match with zero operations.
In the third test case, no matter how the operations are performed, $s$ and $t$ cannot be made to match.

API Response (JSON)

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      "content": "You are given strings $s$ and $t$ of length $N$ consisting of `0` and `1`. Determine whether it is possible to make $s$ match $t$ by performing the following operation at least $0$ and at most $N+1$ t",
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    "platform": "AtCoder",
    "limit": {
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    "difficulty": "None",
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      "content": "You are given strings $s$ and $t$ of length $N$ consisting of `0` and `1`. Determine whether it is possible to make $s$ match $t$ by performing the following operation at least $0$ and at most $N+1$ t...",
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