Codeforces Round 559 (Div. 1)
B
The minimal unique substring
Codeforces
2200
原题
← AC →
翻译中…

Let $s$ be some string consisting of symbols "0" or "1". Let's call a string $t$ a substring of string $s$, if there exists such number $1 \leq l \leq |s| - |t| + 1$ that $t = s_l s_{l+1} \ldots s_{l + |t| - 1}$. Let's call a substring $t$ of string $s$ unique, if there exist only one such $l$.

翻译中…

For example, let $s = $"1010111". A string $t = $"010" is an unique substring of $s$, because $l = 2$ is the only one suitable number. But, for example $t = $"10" isn't a unique substring of $s$, because $l = 1$ and $l = 3$ are suitable. And for example $t =$"00" at all isn't a substring of $s$, because there is no suitable $l$.

翻译中…

Today Vasya solved the following problem at the informatics lesson: given a string consisting of symbols "0" and "1", the task is to find the length of its minimal unique substring. He has written a solution to this problem and wants to test it. He is asking you to help him.

翻译中…

You are given $2$ positive integers $n$ and $k$, such that $(n \bmod 2) = (k \bmod 2)$, where $(x \bmod 2)$ is operation of taking remainder of $x$ by dividing on $2$. Find any string $s$ consisting of $n$ symbols "0" or "1", such that the length of its minimal unique substring is equal to $k$.

翻译中…

Input

翻译中…

The first line contains two integers $n$ and $k$, separated by spaces ($1 \leq k \leq n \leq 100\,000$, $(k \bmod 2) = (n \bmod 2)$).

翻译中…

Output

翻译中…

Print a string $s$ of length $n$, consisting of symbols "0" and "1". Minimal length of the unique substring of $s$ should be equal to $k$. You can find any suitable string. It is guaranteed, that there exists at least one such string.

翻译中…

Note

翻译中…

In the first test, it's easy to see, that the only unique substring of string $s = $"1111" is all string $s$, which has length $4$.

翻译中…

In the second test a string $s = $"01010" has minimal unique substring $t =$"101", which has length $3$.

翻译中…

In the third test a string $s = $"1011011" has minimal unique substring $t =$"110", which has length $3$.

翻译中…

样例

Input #1
4 4
Output #1
1111
InputCopy OutputCopy
Input #2
5 3
Output #2
01010
InputCopy OutputCopy
Input #3
7 3
Output #3
1011011
InputCopy OutputCopy
题目信息
题号
1158B
时间限制
1 s
内存限制
256 MB
标签
构造
数学
字符串

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