zoukankan      html  css  js  c++  java
  • leetcode 31-40 easy

    38、Count and Say

    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, 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"

    C+

    class Solution {
    public:
        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;
    }
    };

    python

    Solution 1 ... using a regular expression
    def countAndSay(self, n):
        s = '1'
        for _ in range(n - 1):
            s = re.sub(r'(.)1*', lambda m: str(len(m.group(0))) + m.group(1), s)
        return s
    Solution
    2 ... using a regular expression def countAndSay(self, n): s = '1' for _ in range(n - 1): s = ''.join(str(len(group)) + digit for group, digit in re.findall(r'((.)2*)', s)) return s
    Solution
    3 ... using groupby def countAndSay(self, n): s = '1' for _ in range(n - 1): s = ''.join(str(len(list(group))) + digit for digit, group in itertools.groupby(s)) return s
  • 相关阅读:
    使用Speex中的AEC模块,提高声音质量(转)
    音频编解码speex库的使用方法
    VC 多线程编程(转)
    并口、串口、COM口区别
    用GDB调试程序
    [转]PCM文件格式
    PreTranslateMessage作用和使用方法
    音频编解码标准
    VS2010 运行速度加快方法(转)
    ON_COMMAND ON_MESSAGE ON_NOTIFY区别与联系
  • 原文地址:https://www.cnblogs.com/hotsnow/p/9585311.html
Copyright © 2011-2022 走看看