Reversing and Concatenating

AtCoder

IDagc037_e

Time2000ms

Memory256MB

Difficulty—

Takahashi has a string $S$ of length $N$ consisting of lowercase English letters. On this string, he will perform the following operation $K$ times: * Let $T$ be the string obtained by reversing $S$, and $U$ be the string obtained by concatenating $S$ and $T$ in this order. * Let $S'$ be some contiguous substring of $U$ with length $N$, and replace $S$ with $S'$. Among the strings that can be the string $S$ after the $K$ operations, find the lexicographically smallest possible one. ## Constraints * $1 \leq N \leq 5000$ * $1 \leq K \leq 10^9$ * $|S|=N$ * $S$ consists of lowercase English letters. ## Input Input is given from Standard Input in the following format: $N$ $K$ $S$ [samples]

Samples

Input #1

5 1
bacba

Output #1

aabca

When $S=$`bacba`, $T=$`abcab`, $U=$`bacbaabcab`, and the optimal choice of $S'$ is $S'=$`aabca`.

Input #2

10 2
bbaabbbaab

Output #2

aaaabbaabb

API Response (JSON)

{
  "problem": {
    "name": "Reversing and Concatenating",
    "description": {
      "content": "Takahashi has a string $S$ of length $N$ consisting of lowercase English letters. On this string, he will perform the following operation $K$ times: *   Let $T$ be the string obtained by reversing $S",
      "description_type": "Markdown"
    },
    "platform": "AtCoder",
    "limit": {
      "time_limit": 2000,
      "memory_limit": 262144
    },
    "difficulty": "None",
    "is_remote": true,
    "is_sync": true,
    "sync_url": null,
    "sign": "agc037_e"
  },
  "statements": [
    {
      "statement_type": "Markdown",
      "content": "Takahashi has a string $S$ of length $N$ consisting of lowercase English letters. On this string, he will perform the following operation $K$ times:\n\n*   Let $T$ be the string obtained by reversing $S...",
      "is_translate": false,
      "language": "English"
    }
  ]
}

Full JSON Raw Segments