leetcode Count and Say 38-优快云博客

本文链接：https://blog.youkuaiyun.com/zzc8265020/article/details/45743153

本文详细解析了Count-and-Say序列的生成过程，包括算法实现、核心逻辑及应用实例，旨在帮助读者理解这一有趣数学序列的生成机制。

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The count-and-say sequence is the sequence of integers begining as follows：

1,11,21,1211,111221，...

1 is read off as "one 1" or 11

11 is read off as "two one" 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

翻译：count-and-say序列是整数开始的序列如下:

1,11,21,1211,111221，...

1读为 "one 1" 或 11

11读为 "two one" 或 21;

21读为 "one 2 , then one 1" 或 1211;

给定一个整数n,n的序列生成
注意:整数序列将被表示为一个字符串

	public static String countAndSay2(int n)
	{
		if(n==1)
		{
			return "1";
		}
		String s="1";
		StringBuffer sb=new StringBuffer();
		//count是出现的次数
		int count=0;
		//round是迭代的次数
		int round=0;
		int i;
		while (++round<n)
		{
			count=1;
			sb.setLength(0);
			for (i = 1; i < s.length(); i++)
			{
				if(s.charAt(i)==s.charAt(i-1))
				{
					count++;
				}
				//有新值出现，记录到sb中
				else
				{
					sb.append(count).append(s.charAt(i-1));
					//重置count
					count=1;
				}
			}
			sb.append(count).append(s.charAt(i-1));
			s=sb.toString();
		}
		return sb.toString();
	}