1+ package com .leetcode .strings ;
2+ 3+ /**
4+ * Problem: https://leetcode.com/problems/count-and-say/
5+ *
6+ * @author rampatra
7+ * @since 2019年04月20日
8+ */
9+ public class CountAndSay {
10+ 11+ /**
12+ * Time complexity:
13+ * Runtime: <a href="https://leetcode.com/submissions/detail/223728660/">1 ms</a>.
14+ *
15+ * @param n
16+ * @return
17+ */
18+ public static String countAndSay (int n ) {
19+ if (n == 1 ) return "1" ;
20+ 21+ String s = countAndSay (n - 1 );
22+ StringBuilder sb = new StringBuilder ();
23+ int count = 0 ;
24+ 25+ for (int i = 0 ; i < s .length (); i ++) {
26+ count ++;
27+ 28+ if (i + 1 >= s .length () || s .charAt (i ) != s .charAt (i + 1 )) {
29+ sb .append (count );
30+ sb .append (s .charAt (i ));
31+ count = 0 ;
32+ }
33+ }
34+ 35+ return sb .toString ();
36+ }
37+ 38+ public static void main (String [] args ) {
39+ System .out .println (countAndSay (1 ));
40+ System .out .println (countAndSay (2 ));
41+ System .out .println (countAndSay (3 ));
42+ System .out .println (countAndSay (4 ));
43+ System .out .println (countAndSay (5 ));
44+ System .out .println (countAndSay (6 ));
45+ System .out .println (countAndSay (10 ));
46+ }
47+ }
0 commit comments