[{
  "_exerciseType": "Comment: DFA, NFA, REGEXP, GRAMMAR, PDA, TM",
  "exerciseType": "REGEXP",
  "totalTrueCases": 9,
  "totalFalseCases": 2,
  "containLetters": ["a", "b"],
  "randomStringLength": [0, 15],
  "description": "Give a regular expression whose language is strings over $\\{a, b\\}$ in which the number of a's is divisible by 3.",
  "testCases": [
    {
      "": true,
      "ShowTestCase": true
    },
    {
      "bbbbbbbbbbb": true,
      "ShowTestCase": true
    },
    {
      "a": false,
      "ShowTestCase": true
    },
    {
      "babab": false,
      "ShowTestCase": true
    },
    {
      "aaa": true,
      "ShowTestCase": true
    },
    {
      "bbbaaa": true,
      "ShowTestCase": true
    },
    {
      "babaa": true,
      "ShowTestCase": true
    },
    {
      "bababa": true,
      "ShowTestCase": true
    },
    {
      "aaabbbbbb": true,
      "ShowTestCase": true
    },
    {
      "aaabbbababbba": true,
      "ShowTestCase": true
    },
    {
      "aaaaaaaaaaaaaaa": true,
      "ShowTestCase": true
    }
  ],
  "graph": {
    "nodes": [],
    "edges": []
  },
  "solution": ""
}]