420. Count and Say【LintCode java】

Description

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.

The sequence of integers will be represented as a string.

Example

Given n = 5, return "111221".

解题：这题目不太好理解，第一个数是 1，第二个数是第一个数的读法，依次类推。参考：https://www.2cto.com/kf/201502/375593.html

代码如下：

public class Solution {
    /**
     * @param n: the nth
     * @return: the nth sequence
     */
    public String countAndSay(int n) {
        // write your code here
        if(n == 1)
             return "1";

        String temp = countAndSay(n - 1) + "*";
        char[]c = temp.toCharArray();
        int count = 1;
        String res = "";
        for(int i = 0; i < c.length - 1; i++){
            if(c[i] == c[i+1]){
                count++;
            }else{
                res = res + count + c[i];
                count = 1;//count归0
            }
        }
        return res;
    }
}