字符串---Count and Say

最新推荐文章于 2024-06-29 09:14:49 发布

zjj2015

最新推荐文章于 2024-06-29 09:14:49 发布

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本文介绍了一种生成计数并说序列的方法，通过迭代构建序列。从初始字符串'1'开始，每一步通过计数相邻重复字符并记录其数量及字符本身来生成新的序列。

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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.

Have you met this question in a real interview? Yes
Example
Given n = 5, return “111221”.



public class Solution {
    public String countAndSay(int n) {
        String oldString = "1";
        while (--n > 0) {
            StringBuffer s = new StringBuffer();
            char [] oldChars = oldString.toCharArray();

            for (int i = 0; i < oldChars.length; i++) {
                int count = 1;
                while ((i+1) < oldChars.length && oldChars[i] == oldChars[i+1]) {
                    count++;
                    i++;
                }
                s.append(String.valueOf(count) + String.valueOf(oldChars[i]));
            }
            oldString = s.toString();
        }

        return oldString;
    }
}