38. Count and Say ★

题目内容：

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 n^th sequence.

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

题目分析：

此题使用StringBuffer构造数组，注意StringBuffer在执行函数操作后返回的仍然是该对象，需要输出数组时不要忘了使用toString函数。

题目代码：

public class Solution {
    public static String countAndSay(int n) {
    StringBuilder curr = new StringBuilder("1");
StringBuilder now = new StringBuilder(); 
    for(int i=1;i<n;i++){    
    now = curr;
    char say = now.charAt(0);
    curr = new StringBuilder();
    int count = 1;
    for(int j=1;j<now.length();j++){
    if(now.charAt(j)!=say){
    curr.append(count).append(say);
    count = 1;
    say = now.charAt(j);
    }
    else count++;
    }
    curr.append(count).append(say);
    }
    return curr.toString();
    }
}