Leetcode 面试题 01.06. 字符串压缩 （字符串模拟）

 输入："aabcccccaaa"
 输出："a2b1c5a3"

 输入："abbccd"
 输出："abbccd"
 解释："abbccd"压缩后为"a1b2c2d1"，比原字符串长度更长。

class Solution {
    #define ll long long
    #define rg register ll
public:
    string compressString(string S) {
        string tepp;
        for(rg i=0;S[i];i++)
        {
            ll tep=i,sum=0;
            string shu;
            tepp+=S[i];
            while(S[tep]==S[i])tep++,sum++;
            while(sum)
            {
                shu+=sum%10+48;
                sum/=10;
            }
            reverse(shu.begin(),shu.end());
            tepp+=shu;
            i=tep-1;
        }
        return tepp.size()>=S.size()?S:tepp;
    }
};