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 Solution { /**It is simple problem. * @author Averill Zheng * @version 2014-06-07 * @since JDK 1.7 */ public String countAndSay(int n) { String result = "1"; for(int i = 1; i < n; ++i){ StringBuffer resultBuffer = new StringBuffer(); int length = result.length(); char currentChar = result.charAt(0); int count = 0; for(int j = 0; j < length; ++j){ if(currentChar != result.charAt(j)){ resultBuffer.append(count); resultBuffer.append(currentChar - '0'); currentChar = result.charAt(j); count = 1; } else ++count; } resultBuffer.append(count); resultBuffer.append(currentChar - '0'); result = resultBuffer.toString(); } return result; } }