CF1861B.Two Binary Strings

You are given two strings $a$ and $b$ of equal length, consisting of only characters 0 and/or 1; both strings start with character 0 and end with character 1.

You can perform the following operation any number of times (possibly zero):

• choose one of the strings and two equal characters in it; then turn all characters between them into those characters.

Formally, you choose one of these two strings (let the chosen string be $s$), then pick two integers $l$ and $r$ such that $1 \le l \lt r \le |s|$ and $s_l = s_r$, then replace every character $s_i$ such that $l \lt i \lt r$ with $s_l$.

For example, if the chosen string is 010101, you can transform it into one of the following strings by applying one operation:

• 000101 if you choose $l = 1$ and $r = 3$;
• 000001 if you choose $l = 1$ and $r = 5$;
• 010001 if you choose $l = 3$ and $r = 5$;
• 010111 if you choose $l = 4$ and $r = 6$;
• 011111 if you choose $l = 2$ and $r = 6$;
• 011101 if you choose $l = 2$ and $r = 4$.

You have to determine if it's possible to make the given strings equal by applying this operation any number of times.

给你两个长度相等的字符串 $a$ 和 $b$，它们仅由字符 0 和/或 1 组成；且两个字符串均以字符 0 开头、以字符 1 结尾。

你可以执行以下操作任意多次（包括零次）：

• 选择其中一个字符串，并在其中选取两个相等的字符；然后将这两个字符之间的所有字符都变为该字符。

形式化地，你选择这两个字符串中的一个（设其为 $s$），再选取两个整数 $l$ 和 $r$，满足 $1 \le l \lt r \le |s|$ 且 $s_l = s_r$，然后将所有满足 $l \lt i \lt r$ 的字符 $s_i$ 替换为 $s_l$。

例如，若所选字符串为 010101，则通过一次操作可将其变为以下字符串之一：

• 000101（当选择 $l = 1$ 且 $r = 3$ 时）；
• 000001（当选择 $l = 1$ 且 $r = 5$ 时）；
• 010001（当选择 $l = 3$ 且 $r = 5$ 时）；
• 010111（当选择 $l = 4$ 且 $r = 6$ 时）；
• 011111（当选择 $l = 2$ 且 $r = 6$ 时）；
• 011101（当选择 $l = 2$ 且 $r = 4$ 时）。

你需要判断：是否可以通过任意次执行该操作，使得给定的两个字符串变得相等。

The first line contains a single integer $t$ ($1 \le t \le 2000$) — the number of test cases.

Each test case consists of two lines:

• the first line contains the string $a$ ($2 \le |a| \le 5000$), consisting of only characters 0 and/or 1.
• the second line contains the string $b$ ($2 \le |b| \le 5000$), consisting of only characters 0 and/or 1.

Additional constraints on the input:

• in each test case, $|a| = |b|$ (the strings have equal length);
• in each test case, both strings start with 0 and end with 1;
• the total length of all strings $a$ in all test cases does not exceed $5000$.

第一行包含一个整数 $t$（$1 \le t \le 2000$）—— 测试用例的数量。

每个测试用例由两行组成：

• 第一行包含字符串 $a$（$2 \le |a| \le 5000$），仅由字符 0 和/或 1 组成；
• 第二行包含字符串 $b$（$2 \le |b| \le 5000$），仅由字符 0 和/或 1 组成。

输入的额外约束条件：

• 在每个测试用例中，$|a| = |b|$（两个字符串长度相等）；
• 在每个测试用例中，两个字符串均以 0 开头、以 1 结尾；
• 所有测试用例中字符串 $a$ 的总长度不超过 $5000$。

For each test case, print YES if it is possible to make the strings equal. Otherwise, print NO. You can print each letter in any register.

对于每个测试用例，如果可以使两个字符串相等，则输出 YES；否则输出 NO。你可以以任意大小写形式输出每个字母。

In the first test case, we can perform the following operations:

1. choose the string $a$, $l = 2$, $r = 4$; after this operation, $a$ is 01110001, $b$ is 01110101;
2. choose the string $b$, $l = 5$, $r = 7$; after this operation, $a$ is 01110001, $b$ is 01110001.

In the second test case, the strings are already equal.

In the third test case, we can perform the following operations:

1. choose the string $a$, $l = 4$, $r = 6$; after this operation, $a$ is 000111, $b$ is 010111;
2. choose the string $b$, $l = 1$, $r = 3$; after this operation, $a$ is 000111, $b$ is 000111;

In the fourth and fifth test cases, it's impossible to make the given strings equal.

在第一个测试用例中，我们可以执行以下操作：

1. 选择字符串 $a$，$l = 2$，$r = 4$；执行该操作后，$a$ 变为 01110001，$b$ 变为 01110101；
2. 选择字符串 $b$，$l = 5$，$r = 7$；执行该操作后，$a$ 为 01110001，$b$ 为 01110001。

在第二个测试用例中，两个字符串已经相等。

在第三个测试用例中，我们可以执行以下操作：

1. 选择字符串 $a$，$l = 4$，$r = 6$；执行该操作后，$a$ 变为 000111，$b$ 变为 010111；
2. 选择字符串 $b$，$l = 1$，$r = 3$；执行该操作后，$a$ 为 000111，$b$ 为 000111。

在第四和第五个测试用例中，无法使给定的字符串相等。