CODE 95. Count and Say

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版权声明：本文为博主原创文章，转载请注明出处：http://blog.jerkybible.com/2013/10/29/2013-10-29-CODE 95 Count and Say/

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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 String countAndSay(int n) {
	// IMPORTANT: Please reset any member data you declared, as
	// the same Solution instance will be reused for each test case.
	if (n <= 0) {
		return "";
	}
	String string = null;
	for (int i = 1; i <= n; i++) {
		if (1 == i) {
			string = "1";
		} else {
			char[] cs = string.toCharArray();
			char tmp = cs[0];
			int tmpnum = 1;
			StringBuilder sb = new StringBuilder();
			for (int j = 1; j < cs.length; j++) {
				if (cs[j] == tmp) {
					tmpnum++;
				} else {
					sb.append(tmpnum);
					sb.append(tmp);
					tmp = cs[j];
					tmpnum = 1;
				}
			}
			sb.append(tmpnum);
			sb.append(tmp);
			string = null;
			string = sb.toString();
		}
	}
	return string;
}