今天發現C++ 11中推出了一個非常有用的函式 to_string() , 非常有效的解決了C++中其他型別（數字）轉換成string。咱們再也不用麻煩的使用stringstream去轉換了。貼上一個code，Leetcode中Count and Say 

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

1 is read off as "one 1" or 11.
11 is read off as "two 1s" or 21

Given an integer n, generate the nth sequence.

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

class Solution {
public:
    string countAndSay(int n) {
        int i=1;
        string val=to_string(1);
        while(i<n){
            val=getSequence(val);
            i++;
        }
        return val;
    }
    
    string getSequence(string val){
        int cnt=1;
        string newstr="";
        int i;
        for(i=0;i<val.length()-1;i++){
            if(val[i+1]==val[i]) cnt++;
            else{
                newstr=newstr+to_string(cnt)+val[i]; //有木有看到這裡閃亮的 to_string() !
                cnt=1;
            }
        }
        newstr=newstr+to_string(cnt)+val[i];
        return newstr;
    }
};