[LeetCode]38.Count and Say

【题目】

The count-and-say sequence is the sequence of integers beginning as follows:
1, 11, 21, 1211, 111221, ...

1is read off as"one 1"or11.
11is read off as"two 1s"or21.
21is read off as"one 2, thenone 1"or1211.

Given an integern, generate thenthsequence.

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

【分析】

111221 统计相邻重复的字符个数，例如这里111有3个1重复相邻，输出31，22有两个2重复相邻，输出22，1只有一个1，输出11

【代码】

/*********************************
*   日期：2015-01-27
*   作者：SJF0115
*   题目: 38.Count and Say
*   网址：https://oj.leetcode.com/problems/count-and-say/
*   结果：AC
*   来源：LeetCode
*   博客：
**********************************/
#include <iostream>
using namespace std;

class Solution {
public:
    string countAndSay(int n) {
        if(n <= 0){
            return "";
        }//if
        string str("1");
        for(int i = 1;i < n;++i){
            NextCountAndSay(str);
        }//for
        return str;
    }
private:
    void NextCountAndSay(string& str){
        int len = str.length();
        string tmp = "";
        for(int i = 0;i < len;++i){
            int repeatCount = 1;
            // repeat char count
            while((i+1 < len) && (str[i] == str[i+1])){
                ++repeatCount;
                ++i;
            }//
            tmp += to_string(repeatCount);
            tmp += str[i];
        }//for
        str = tmp;
    }
};

int main(){
    Solution solution;
    int n = 5;
    string result = solution.countAndSay(n);
    // 输出
    cout<<result<<endl;
    return 0;
}