[Leetcode]Count and Say

最新推荐文章于 2025-12-21 17:04:13 发布

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本文详细解析了Count-and-Say序列的生成逻辑，并提供了一个优化后的代码实现，旨在快速生成任意阶数的序列。通过遍历并计数连续字符，逐级构建序列，实现高效计算。

The count-and-say sequence is the sequence of integers beginning as follows:
1, 11, 21, 1211, 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, generate the nth sequence.

Note: The sequence of integers will be represented as a string.

如果有更好更高效的代码，希望大家共享~

class Solution {
public:
    string countAndSay(int n) {
        string seq = "1";
        string result = "";
        int count = 1;
        char pre;
        if(n > 1)
        {
            for (int i = 2; i <= n; i++)
            {
                pre = ' ';
                for (int j = 0; j < seq.size(); j++)
                {
                    if(j + 1 < seq.size() && seq[j + 1] == seq[j])
                    {
                        count++;
                    }
                    else
                    {
                        pre = seq[j];
                        result.push_back(count + '0');
                        result.push_back(pre);
                        count = 1;
                    }
                }
                seq = result;
                result = "";
            }
            return seq;
        }
        else if(n == 1)
        {
            return "1";
        }
    }
};

本文不详尽或错误之处，请各位不吝言辞，多多指教~谢谢~

作者：Louise http://blog.youkuaiyun.com/yupingliu