A13185. Erase Subsequences
编程题
普及/提高-
知识点
题目描述
You are given a string $s$ . You can build new string $p$ from $s$ using the following operation no more than two times:
1. choose any subsequence $s_{i_1}, s_{i_2}, \dots, s_{i_k}$ where $1 \le i_1 < i_2 < \dots < i_k \le |s|$ ;
2. erase the chosen subsequence from $s$ ( $s$ can become empty);
3. concatenate chosen subsequence to the right of the string $p$ (in other words, $p = p + s_{i_1}s_{i_2}\dots s_{i_k}$ ).
Of course, initially the string $p$ is empty.
For example, let $s = \text{ababcd}$ . At first, let's choose subsequence $s_1 s_4 s_5 = \text{abc}$ — we will get $s = \text{bad}$ and $p = \text{abc}$ . At second, let's choose $s_1 s_2 = \text{ba}$ — we will get $s = \text{d}$ and $p = \text{abcba}$ . So we can build $\text{abcba}$ from $\text{ababcd}$ .
Can you build a given string $t$ using the algorithm above?
1. choose any subsequence $s_{i_1}, s_{i_2}, \dots, s_{i_k}$ where $1 \le i_1 < i_2 < \dots < i_k \le |s|$ ;
2. erase the chosen subsequence from $s$ ( $s$ can become empty);
3. concatenate chosen subsequence to the right of the string $p$ (in other words, $p = p + s_{i_1}s_{i_2}\dots s_{i_k}$ ).
Of course, initially the string $p$ is empty.
For example, let $s = \text{ababcd}$ . At first, let's choose subsequence $s_1 s_4 s_5 = \text{abc}$ — we will get $s = \text{bad}$ and $p = \text{abc}$ . At second, let's choose $s_1 s_2 = \text{ba}$ — we will get $s = \text{d}$ and $p = \text{abcba}$ . So we can build $\text{abcba}$ from $\text{ababcd}$ .
Can you build a given string $t$ using the algorithm above?
输入格式
The first line contains the single integer $T$ ( $1 \le T \le 100$ ) — the number of test cases.
Next $2T$ lines contain test cases — two per test case. The first line contains string $s$ consisting of lowercase Latin letters ( $1 \le |s| \le 400$ ) — the initial string.
The second line contains string $t$ consisting of lowercase Latin letters ( $1 \le |t| \le |s|$ ) — the string you'd like to build.
It's guaranteed that the total length of strings $s$ doesn't exceed $400$ .
Next $2T$ lines contain test cases — two per test case. The first line contains string $s$ consisting of lowercase Latin letters ( $1 \le |s| \le 400$ ) — the initial string.
The second line contains string $t$ consisting of lowercase Latin letters ( $1 \le |t| \le |s|$ ) — the string you'd like to build.
It's guaranteed that the total length of strings $s$ doesn't exceed $400$ .
输出格式
Print $T$ answers — one per test case. Print YES (case insensitive) if it's possible to build $t$ and NO (case insensitive) otherwise.
输入输出样例
输入 #1
4 ababcd abcba a b defi fed xyz x
输出 #1
YES NO NO YES