A14068 | Binary Removals
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内存限制256MB
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题目描述
You are given a string $s$ , consisting only of characters '0' or '1'. Let $|s|$ be the length of $s$ .
You are asked to choose some integer $k$ ( $k > 0$ ) and find a sequence $a$ of length $k$ such that:
- $1 \le a_1 < a_2 < \dots < a_k \le |s|$ ;
- $a_{i-1} + 1 < a_i$ for all $i$ from $2$ to $k$ .
The characters at positions $a_1, a_2, \dots, a_k$ are removed, the remaining characters are concatenated without changing the order. So, in other words, the positions in the sequence $a$ should not be adjacent.
Let the resulting string be $s'$ . $s'$ is called sorted if for all $i$ from $2$ to $|s'|$ $s'_{i-1} \le s'_i$ .
Does there exist such a sequence $a$ that the resulting string $s'$ is sorted?
You are asked to choose some integer $k$ ( $k > 0$ ) and find a sequence $a$ of length $k$ such that:
- $1 \le a_1 < a_2 < \dots < a_k \le |s|$ ;
- $a_{i-1} + 1 < a_i$ for all $i$ from $2$ to $k$ .
The characters at positions $a_1, a_2, \dots, a_k$ are removed, the remaining characters are concatenated without changing the order. So, in other words, the positions in the sequence $a$ should not be adjacent.
Let the resulting string be $s'$ . $s'$ is called sorted if for all $i$ from $2$ to $|s'|$ $s'_{i-1} \le s'_i$ .
Does there exist such a sequence $a$ that the resulting string $s'$ is sorted?
输入格式
The first line contains a single integer $t$ ( $1 \le t \le 1000$ ) — the number of testcases.
Then the descriptions of $t$ testcases follow.
The only line of each testcase contains a string $s$ ( $2 \le |s| \le 100$ ). Each character is either '0' or '1'.
Then the descriptions of $t$ testcases follow.
The only line of each testcase contains a string $s$ ( $2 \le |s| \le 100$ ). Each character is either '0' or '1'.
输出格式
For each testcase print "YES" if there exists a sequence $a$ such that removing the characters at positions $a_1, a_2, \dots, a_k$ and concatenating the parts without changing the order produces a sorted string.
Otherwise, print "NO".
You may print every letter in any case you want (so, for example, the strings yEs, yes, Yes and YES are all recognized as positive answer).
Otherwise, print "NO".
You may print every letter in any case you want (so, for example, the strings yEs, yes, Yes and YES are all recognized as positive answer).
输入输出样例
输入 #1
5 10101011011 0000 11111 110 1100
输出 #1
YES YES YES YES NO
In the first testcase you can choose a sequence $a=[1,3,6,9]$ . Removing the underlined letters from "10101011011" will produce a string "0011111", which is sorted.
In the second and the third testcases the sequences are already sorted.
In the fourth testcase you can choose a sequence $a=[3]$ . $s'=$ "11", which is sorted.
In the fifth testcase there is no way to choose a sequence $a$ such that $s'$ is sorted.
In the second and the third testcases the sequences are already sorted.
In the fourth testcase you can choose a sequence $a=[3]$ . $s'=$ "11", which is sorted.
In the fifth testcase there is no way to choose a sequence $a$ such that $s'$ is sorted.
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