K-th Substring

AtCoder

IDarc097_a

Time2000ms

Memory256MB

Difficulty—

You are given a string $s$. Among the **different** substrings of $s$, print the $K$\-th lexicographically smallest one. A substring of $s$ is a string obtained by taking out a non-empty contiguous part in $s$. For example, if $s$ $=$ `ababc`, `a`, `bab` and `ababc` are substrings of $s$, while `ac`, `z` and an empty string are not. Also, we say that substrings are different when they are different as strings. Let $X = x_{1}x_{2}...x_{n}$ and $Y = y_{1}y_{2}...y_{m}$ be two distinct strings. $X$ is lexicographically larger than $Y$ if and only if $Y$ is a prefix of $X$ or $x_{j} > y_{j}$ where $j$ is the smallest integer such that $x_{j} \neq y_{j}$. ## Constraints * $1$ $≤$ $|s|$ $≤$ $5000$ * $s$ consists of lowercase English letters. * $1$ $≤$ $K$ $≤$ $5$ * $s$ has at least $K$ different substrings. ## Input Input is given from Standard Input in the following format: $s$ $K$ ## Partial Score * $200$ points will be awarded as a partial score for passing the test set satisfying $|s|$ $≤$ $50$. [samples]

Samples

Input #1

aba
4

Output #1

b

$s$ has five substrings: `a`, `b`, `ab`, `ba` and `aba`. Among them, we should print the fourth smallest one, `b`. Note that we do not count `a` twice.

Input #2

atcoderandatcodeer
5

Output #2

andat

Input #3

z
1

Output #3

API Response (JSON)

{
  "problem": {
    "name": "K-th Substring",
    "description": {
      "content": "You are given a string $s$. Among the **different** substrings of $s$, print the $K$\\-th lexicographically smallest one. A substring of $s$ is a string obtained by taking out a non-empty contiguous pa",
      "description_type": "Markdown"
    },
    "platform": "AtCoder",
    "limit": {
      "time_limit": 2000,
      "memory_limit": 262144
    },
    "difficulty": "None",
    "is_remote": true,
    "is_sync": true,
    "sync_url": null,
    "sign": "arc097_a"
  },
  "statements": [
    {
      "statement_type": "Markdown",
      "content": "You are given a string $s$. Among the **different** substrings of $s$, print the $K$\\-th lexicographically smallest one.\nA substring of $s$ is a string obtained by taking out a non-empty contiguous pa...",
      "is_translate": false,
      "language": "English"
    }
  ]
}

Full JSON Raw Segments