String Equivalence

AtCoder

IDpanasonic2020_d

Time2000ms

Memory256MB

Difficulty—

In this problem, we only consider strings consisting of lowercase English letters. Strings $s$ and $t$ are said to be **isomorphic** when the following conditions are satisfied: * $|s| = |t|$ holds. * For every pair $i, j$, one of the following holds: * $s_i = s_j$ and $t_i = t_j$. * $s_i \neq s_j$ and $t_i \neq t_j$. For example, `abcac` and `zyxzx` are isomorphic, while `abcac` and `ppppp` are not. A string $s$ is said to be in **normal form** when the following condition is satisfied: * For every string $t$ that is isomorphic to $s$, $s \leq t$ holds. Here $\leq$ denotes lexicographic comparison. For example, `abcac` is in normal form, but `zyxzx` is not since it is isomorphic to `abcac`, which is lexicographically smaller than `zyxzx`. You are given an integer $N$. Print all strings of length $N$ that are in normal form, in lexicographically ascending order. ## Constraints * $1 \leq N \leq 10$ * All values in input are integers. ## Input Input is given from Standard Input in the following format: $N$ [samples]

Samples

Input #1

Output #1

Input #2

Output #2

aa
ab

API Response (JSON)

{
  "problem": {
    "name": "String Equivalence",
    "description": {
      "content": "In this problem, we only consider strings consisting of lowercase English letters. Strings $s$ and $t$ are said to be **isomorphic** when the following conditions are satisfied: *   $|s| = |t|$ holds",
      "description_type": "Markdown"
    },
    "platform": "AtCoder",
    "limit": {
      "time_limit": 2000,
      "memory_limit": 262144
    },
    "difficulty": "None",
    "is_remote": true,
    "is_sync": true,
    "sync_url": null,
    "sign": "panasonic2020_d"
  },
  "statements": [
    {
      "statement_type": "Markdown",
      "content": "In this problem, we only consider strings consisting of lowercase English letters.\nStrings $s$ and $t$ are said to be **isomorphic** when the following conditions are satisfied:\n\n*   $|s| = |t|$ holds...",
      "is_translate": false,
      "language": "English"
    }
  ]
}

Full JSON Raw Segments