Leetcode 38 Count and Say

最新推荐文章于 2021-01-13 21:28:45 发布

pessis1

最新推荐文章于 2021-01-13 21:28:45 发布

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本文介绍了一个生成计数并描述序列的算法实现。该序列从1开始，后续每一项都是对前一项的计数和描述。例如，1被描述为“一个1”，即11；11被描述为“两个1”，即21；21被描述为“一个2，然后一个1”，即1211。通过递归的方式，文章提供了Java代码来生成指定位置的序列。

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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.

Note: The sequence of integers will be represented as a string.

看半天才看懂题目晕留下一点我笨拙的痕迹

public class Solution {
    public static String countAndSay(int n) {
	        String result = "1";
	        String str="1";
	        String str_next="";
	        int count = 1;
	        for(int i = 0;i< n-1 ;i++){
	        //	System.out.println("i="+i+"str="+str+"str_next="+str_next);
	        	
	            for(int j =0;j<str.length();j++){
	            
	                if(j==str.length()-1){
	              //  	System.out.println("la");
	                	//System.out.println(str_next);
	                	str_next=str_next+count+str.charAt(j);
	                	//System.out.println(str_next);
	                	count = 1;
	                }
	                else if(str.charAt(j)==str.charAt(j+1)){
	                //	System.out.println("lala");
	                    count++;
	                }
	                else{
	                	//System.out.println(str.charAt(j));
	                	//System.out.println(str.charAt(j+1));
	                //	System.out.println("count"+count);
	                    str_next=str_next+count+str.charAt(j);
	                  //  System.out.println("lalala");
	                    count = 1;
	                }
	            }
	            result=str_next;
	            str=str_next;
	            str_next ="";
	        }
	        return result;
	    }
}