LeetCode--No.38--Count and Say

最新推荐文章于 2024-04-25 07:42:53 发布

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最新推荐文章于 2024-04-25 07:42:53 发布

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本文介绍了一种特殊的整数序列——计数读数序列，并提供了一个Java实现方案。该序列从1开始，后续每一项都是对前一项的描述。例如，1被描述为“一个1”，即11；11被描述为“两个1”，即21。文章通过具体示例详细解释了序列的生成逻辑，并给出了完整的代码实现。

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.

1. 题意理解问题
n是个整数，迭代。
代码如下
需要注意的地方：
for循环附近。初始条件要处理好。迭代次数要想明白。

public class Solution {
    public String countAndCount(String s){
        char tmp = s.charAt(0);
        String res = "";
        int num = 0;
        for(int i = 0; i < s.length(); i++){
            char ch = s.charAt(i);
            if (ch == tmp){
                num++;
            }
            else{
                res = res + num + tmp;
                tmp = ch;
                num = 1;
            }
        }
        res = res + num + tmp;
        return res;
    }
    public String countAndSay(int n) {
        String str = "1";
        for(int i = 1; i < n; i++){
            str = countAndCount(str);
        }
        return str;
    }
}