Count and Say

问题：1,11,21,1211,111221。输出这类字符窜，1211的后面那个字符窜就是解释这个字符窜，1个1,1个2,2个1 
分析：每次数字符窜，当数到s[j]和前一个不同的话就进行记录

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

class Solution { public:     string countAndSay(int n) {         int k=0,i,j;         string s1,s2;         s1+='1';           for(i=1;i<n;i++)         {             //cout<<s1<<endl;             s2.clear();             int sum=0,c=-3;             for(j=0;j<s1.size();j++)             {                 if(j!=0 && s1[j]!=c)                 {                     s2+=sum+'0';                     s2+=c;                     sum=0;                 }                 c=s1[j];                 sum++;             }             s2+=sum+'0';             s2+=c;             s1=s2;         }         return s1;     } };