[leetcode] Count and Say

Count and Say

  Total Accepted: 29451  Total Submissions: 114094 My Submissions

Question  Solution 

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.

package com.wyt.leetcodeOJ;

/**
 * @author wangyitao
 * @Date 2015-01-23
 * @version
 * @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. Note: The sequence of integers will be represented
 *              as a string.
 *
 */
public class CountandSay {

	public static void main(String[] args) {
		System.out.println(countAndSay(6));
	}

	public static String countAndSay(int n) {
		String str = "1";
		if (n == 1) {
			return str;
		}
		for (int i = 2; i <= n; i++) {
			str = getTmp(str);
		}
		return str;
	}

	public static String getTmp(String nstr) {
		String str = "";
		char tmp;
		tmp = nstr.charAt(0);
		int count = 0;
		for (int i = 0; i < nstr.length(); i++) {
			if (nstr.charAt(i) == tmp) {
				count++;
			} else {
				str += count;
				str += tmp;
				tmp = nstr.charAt(i);
				count = 1;
			}
		}
		str += count;
		str += tmp;
		return str;
	}
}