[leetcode]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.

21 is read off as "one 2, then
one 1" or 1211.
Given an integer n, generate the nth sequence.
Note: The sequence of integers will be represented as a string.

此题没找到简单的方法
n-1时候生成的former 字符串，一次读出其中的每个字符，比较former[i]与former[i+1]是否相同，不相同依次写入 count 和数 即可

string countAndSay(int n) {
string former="1";
for(int i=1; i<n; i++){
unsigned long length=former.length();
int k=0;
string temp;
int count=1;
while(k<length){
if(former[k]!=former[k+1]){
temp+='0'+count;
temp+=former[k];
count=1;
}
else{
count++;
}
k++;
}
former=temp;
}
return former;
}