LeetCode Count and Say

最新推荐文章于 2025-12-03 23:35:37 发布

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本文介绍了一种通过直接模拟实现的算法，用于生成著名的计数并说（Count and Say）数学序列。该序列从数字1开始，后续每一项都是对前一项的描述。文章详细解释了序列的构造原理，并提供了一个具体的C++实现示例。

题目

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 n^th sequence.

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

直接模拟

代码：

class Solution {
public:
	string toString(int n)	//将数字转化为string
	{
		string ans;
		int radix=1;
		while(n/radix>9)
			radix*=10;
		while(radix>0)
		{
			ans.push_back('0'+n/radix);
			n%=radix;
			radix/=10;
		}
		return ans;
	}
    string countAndSay(int n) {
        string ans="1",temp;
		int i,j,k,len;
		for(i=1;i<n;i++)	//直接模拟
		{
			len=ans.size();
			j=0;
			while(j<len)
			{
				k=j+1;
				while(k<len&&ans[k]==ans[j])
					k++;
				temp+=toString(k-j);
				temp.push_back(ans[j]);
				j=k;
			}
			ans=temp;
			temp.clear();
		}
		return ans;
    }
};