String:38. Count and Say

    我的乱糟糟的代码：

class Solution {
public:
    string countAndSay(int n) {
        string result = "1";
        for(int i = 1; i < n; ++i)
        {
            result = count(result);
            //cout << result << endl;
        }
        return result;
    }
    string count(string s)
    {
        char x = s[0];
        int count = 1;
        string result = "";
        int i = 1;
        for(; i < s.size(); ++i)
        {
            if(s[i] == x)
            {
                count++;
            }
            else
            {
                x = s[i];
                result += '0' + count;
                result += s[i - 1];
                count = 1;
            }
        }
        result += '0' + count;
        result += s[i - 1];
        return result;
    }
};

    稍微改一下下，string里可以访问s.size()的位置，所以不用这么麻烦。

class Solution {
public:
    string countAndSay(int n) {
        string result = "1";
        for(int i = 1; i < n; ++i)
        {
            result = count(result);
            //cout << result << endl;
        }
        return result;
    }
    string count(string s)
    {
        char x = s[0];
        int count = 1;
        string result = "";
        for(int i = 0; i < s.size(); ++i)
        {
            if(s[i + 1] == s[i])
            {
                count++;
            }
            else
            {
                result += '0' + count;
                result += s[i];
                count = 1;
            }
        }
        return result;
    }
};

    更简单的写法：

class Solution {
public:
    string countAndSay(int n) {
        if (n == 1){return "1";}
        if (n == 2){return "11";}
        string result = countAndSay(n-1);
        string newresult = "";
        int count = 1;
        for(int i = 1; i < result.size() + 1; ++i){
            if(result[i] != result[i-1]){
                newresult.push_back('0'+count);
                newresult.push_back(result[i-1]);
                count = 1;
            }else{
                count++;
            }
        }
        return newresult;
    }
    
};