A14918. Deletions of Two Adjacent Letters
编程题
普及/提高-
知识点
题目描述
The string $s$ is given, the string length is odd number. The string consists of lowercase letters of the Latin alphabet.
As long as the string length is greater than $1$ , the following operation can be performed on it: select any two adjacent letters in the string $s$ and delete them from the string. For example, from the string "lemma" in one operation, you can get any of the four strings: "mma", "lma", "lea" or "lem" In particular, in one operation, the length of the string reduces by $2$ .
Formally, let the string $s$ have the form $s=s_1s_2 \dots s_n$ ( $n>1$ ). During one operation, you choose an arbitrary index $i$ ( $1 \le i < n$ ) and replace $s=s_1s_2 \dots s_{i-1}s_{i+2} \dots s_n$ .
For the given string $s$ and the letter $c$ , determine whether it is possible to make such a sequence of operations that in the end the equality $s=c$ will be true? In other words, is there such a sequence of operations that the process will end with a string of length $1$ , which consists of the letter $c$ ?
As long as the string length is greater than $1$ , the following operation can be performed on it: select any two adjacent letters in the string $s$ and delete them from the string. For example, from the string "lemma" in one operation, you can get any of the four strings: "mma", "lma", "lea" or "lem" In particular, in one operation, the length of the string reduces by $2$ .
Formally, let the string $s$ have the form $s=s_1s_2 \dots s_n$ ( $n>1$ ). During one operation, you choose an arbitrary index $i$ ( $1 \le i < n$ ) and replace $s=s_1s_2 \dots s_{i-1}s_{i+2} \dots s_n$ .
For the given string $s$ and the letter $c$ , determine whether it is possible to make such a sequence of operations that in the end the equality $s=c$ will be true? In other words, is there such a sequence of operations that the process will end with a string of length $1$ , which consists of the letter $c$ ?
输入格式
The first line of input data contains an integer $t$ ( $1 \le t \le 10^3$ ) — the number of input test cases.
The descriptions of the $t$ cases follow. Each test case is represented by two lines:
- string $s$ , which has an odd length from $1$ to $49$ inclusive and consists of lowercase letters of the Latin alphabet;
- is a string containing one letter $c$ , where $c$ is a lowercase letter of the Latin alphabet.
The descriptions of the $t$ cases follow. Each test case is represented by two lines:
- string $s$ , which has an odd length from $1$ to $49$ inclusive and consists of lowercase letters of the Latin alphabet;
- is a string containing one letter $c$ , where $c$ is a lowercase letter of the Latin alphabet.
输出格式
For each test case in a separate line output:
- YES, if the string $s$ can be converted so that $s=c$ is true;
- NO otherwise.
You can output YES and NO in any case (for example, the strings yEs, yes, Yes and YES will be recognized as a positive response).
- YES, if the string $s$ can be converted so that $s=c$ is true;
- NO otherwise.
You can output YES and NO in any case (for example, the strings yEs, yes, Yes and YES will be recognized as a positive response).
输入输出样例
输入 #1
5 abcde c abcde b x y aaaaaaaaaaaaaaa a contest t
输出 #1
YES NO NO YES YES
说明/提示
In the first test case, $s$ ="abcde". You need to get $s$ ="c". For the first operation, delete the first two letters, we get $s$ ="cde". In the second operation, we delete the last two letters, so we get the expected value of $s$ ="c".
In the third test case, $s$ ="x", it is required to get $s$ ="y". Obviously, this cannot be done.
In the third test case, $s$ ="x", it is required to get $s$ ="y". Obviously, this cannot be done.