AtCoder Regular Contest 141
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Problem Statement
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You are given $N$ srings $S_i\ (1\le i \le N)$ consisting of A, B, C, D.
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Consider the operation below on a string $T$ consisting of A, B, C, D.
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- Repeat the following until
$T$contains none of the strings$S_i$as a substring. - Choose an
$S_i$and one of its occurrences in$T$, remove that occurrence from$T$, and concatenate the remaining parts.
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What is a substring? A substring of a string is its contiguous subsequence. For example, A, AB, and BC are substrings of ABC, while BA and AC are not.
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We say that the string $T$ is bad when multiple strings can result from the operation above.
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Determine whether a bad string exists.
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Constraints
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$1 \leq N \leq 10^6$$1 \leq |S_i| \leq 2 \times 10^6$$|S_1|+|S_2|+\dots +|S_N| \leq 2 \times 10^6$$S_i \neq S_j$if$i\neq j$.$S_i$is a string consisting ofA,B,C,D.
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Input
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Input is given from Standard Input in the following format:
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N
S_1
S_2
\vdots
S_N
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Output
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If a bad string exists, print Yes.
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Otherwise, print No.
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样例
Input #1
3
A
B
C
Output #1
No
The only string we can get from $T$ is what remains after removing all occurrences of `A`, `B`, `C` from $T$.
Input #2
1
ABA
Output #2
Yes
For example, from $T=$ `ABABA`, we can get two strings: `AB` and `BA`, so $T$ is a bad string.
Input #3
4
CBA
ACB
AD
CAB
Output #3
Yes
题目信息
题面与样例版权归 AtCoder 及出题人所有;中文翻译由 AI 生成(CI 管线),如有出入请以原文为准。