LeetCode——Count and Say

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 n^th sequence.

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

 

暴力之美：

public class Solution {
    public static String[] str = new String[1000000];
	public static void ans() {
		str[1] = "1";
		for(int i=1; i<30; i++) {
			str[i+1] = resolve(str[i]);
		}
	}
	
    public static String countAndSay(int n) {
        ans();
        return str[n];
    }
	
	public static String resolve(String str) {
		StringBuilder res = new StringBuilder();
		for(int i=0; i<str.length(); ) {
			char cur = str.charAt(i);
			int count = 1;
			for(int j=i+1; j<str.length(); j++) {
				if(cur == str.charAt(j)) {
					count ++;
				}
				else {
					break;
				}
			}
			
			res.append(count+"");
			res.append(cur);
			i += count;
		}
		return res.toString();
	}
}