Count and Say

最新推荐文章于 2024-08-01 17:15:16 发布

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最新推荐文章于 2024-08-01 17:15:16 发布

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本文介绍了一种生成计数与说数序列的方法，通过C++代码实现，该序列根据前一项生成下一项，例如从1开始，依次生成11211211111221等。文章提供了完整的代码示例，适用于理解递归序列生成算法。

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The count-and-say sequence is the sequence of integers with the first five terms as following:

1.     1
2.     11
3.     21
4.     1211
5.     111221

1 is read off as "one 1" or 11.
11 is read off as "two 1s" or 21.
21 is read off as "one 2, then one 1" or 1211.

Given an integer n where 1 ≤ n ≤ 30, generate the nth term of the count-and-say sequence.

Note: Each term of the sequence of integers will be represented as a string.

Example 1:

Input: 1
Output: "1"

Example 2:

Input: 4
Output: "1211"

思路：

C++代码：

string countAndSay(int n) {
    if (n == 0) return "";
    string res = "1";
    while (--n) {
        string cur = "";
        for (int i = 0; i < res.size(); i++) {
            int count = 1;
             while ((i + 1 < res.size()) && (res[i] == res[i + 1])){
                count++;    
                i++;
            }
            cur += to_string(count) + res[i];
        }
        res = cur;
    }
    return res;
}