题目链接:https://leetcode.com/problems/count-and-say/?tab=Description
1—>11—>21—>1211—>111221—>312211—>….
按照上面的规律进行求解出第n个字符串是什么。
规律:相连的数字有多少个然后添加上这个数字
参考代码:
package leetcode_50; /*** * * @author pengfei_zheng * 按照规律进行求解字符串 */ public class Solution38 { public static String countAndSay(int n) { if(n<=0) { return ""; } String s="1"; int times = 1; while(times<n){ s = getSay(s); times++; } return s; } private static String getSay(String s) { int count =0; StringBuilder str = new StringBuilder(""); for(int i = 0; i<s.length(); i++){ //first to add in order to prevent thinking about the index count ++; //not reach the end of s and next item is not equal to the pre item if ((i< s.length()-1) && (s.charAt(i) != s.charAt(i + 1))) { str = str.append(count).append(s.charAt(i));//rebuild the str count = 0;//reset count to zero } else if ((i == s.length()-1)) {//meet the end of s str = str.append(count).append(s.charAt(i)); } } return str.toString(); } public static void main(String[]args){ String s = countAndSay(2); System.out.println(s); } }
时间: 2024-10-15 18:30:24