Count and Say

最新推荐文章于 2024-12-21 10:31:21 发布

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最新推荐文章于 2024-12-21 10:31:21 发布

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原文链接：http://www.cnblogs.com/zsychanpin/p/7233326.html

本文介绍了一种生成计数并说序列的方法，通过C++实现了一个递归算法来生成第n项的计数并说序列。代码中包含了完整的解决方案，并详细解释了每一步的操作。

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问题：链接

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.

解答：

没啥意思，数数吧。m_itoa（）是自己实现的一个一位的itoa

代码：

class Solution {
public:
    string countAndSay(int n) {
    
	if(n == 0)
		return "";
	string s = "1";
	for(int i = 1; i < n; i++)
	{
		s = next(s);
	}
	return s;
	
}

	string next(string ls)
	{
		int count;
		char target;
		string temp;
		count = 1;
		target = ls[0];
		string s = "";
		for(int i = 1; i < ls.size(); i++)
		{
			if(target == ls[i])
				++count;
			else
			{
				temp = m_itoa(count);
				s += temp;
				s += target;
				count = 1;
				target = ls[i];
			}
		}
		temp = m_itoa(count);
		s += temp;
		s += target;
		return s;
	}
	string m_itoa(int count)
	{
		string re = "";
		stack<int> st;
		char s[2];
		while(count)
		{
			st.push(count%10);
			count /= 10;
		}
		while(!st.empty())
		{
			s[0] = st.top() + '0';
			s[1] = '\0';
			re.append(s);
			st.pop();
		}
		return re;
	}
};

转载于:https://www.cnblogs.com/zsychanpin/p/7233326.html