{ "data": { "question": { "questionId": "38", "questionFrontendId": "38", "boundTopicId": null, "title": "Count and Say", "titleSlug": "count-and-say", "content": "

The count-and-say sequence is a sequence of digit strings defined by the recursive formula:

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To determine how you "say" a digit string, split it into the minimal number of groups so that each group is a contiguous section all of the same character. Then for each group, say the number of characters, then say the character. To convert the saying into a digit string, replace the counts with a number and concatenate every saying.

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For example, the saying and conversion for digit string "3322251":

\n\"\"\n

Given a positive integer n, return the nth term of the count-and-say sequence.

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Example 1:

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\nInput: n = 1\nOutput: "1"\nExplanation: This is the base case.\n
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Example 2:

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\nInput: n = 4\nOutput: "1211"\nExplanation:\ncountAndSay(1) = "1"\ncountAndSay(2) = say "1" = one 1 = "11"\ncountAndSay(3) = say "11" = two 1's = "21"\ncountAndSay(4) = say "21" = one 2 + one 1 = "12" + "11" = "1211"\n
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Constraints:

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\r\n 1.     1\r\n 2.     11\r\n 3.     21\r\n 4.     1211\r\n 5.     111221 \r\n 6.     312211\r\n 7.     13112221\r\n 8.     1113213211\r\n 9.     31131211131221\r\n10.     13211311123113112211\r\n
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