http://oraqa.com/2007/12/16/how-to-solve-the-josephus-problem-in-sql/ Oracle Question and Answer Mon, 19 Dec 2011 14:21:07 -0700 http://wordpress.org/?v=2.8.4 hourly 1 http://oraqa.com/2007/12/16/how-to-solve-the-josephus-problem-in-sql/comment-page-1/#comment-282 newkid Fri, 25 Jun 2010 16:29:10 +0000 http://oraqa.com/2007/12/16/how-to-solve-the-josephus-problem-in-sql/#comment-282 <pre> 11GR2: WITH t (cnt,people,pos,eliminated) AS ( SELECT MAX(ROWNUM) cnt,MAX(SYS_CONNECT_BY_PATH(LPAD(ROWNUM,4),',')),6,'' FROM DUAL CONNECT BY ROWNUM<=:input_num UNION ALL SELECT cnt-1,SUBSTR(people,1,pos-1)||SUBSTR(people,pos+5) ,CASE WHEN pos+5<LENGTH(SUBSTR(people,1,pos-1)||SUBSTR(people,pos+5)) THEN pos+5 WHEN pos+5<LENGTH(people) THEN 1 ELSE 6 END ,CAST(eliminated||SUBSTR(people,pos,5) AS VARCHAR2(200)) FROM t WHERE cnt>1 ) SELECT people,eliminated FROM t WHERE cnt=1; PEOPLE ------------------------------------------------------- ELIMINATED ------------------------------------------------------- , 5 , 2, 4, 6, 8, 10, 3, 7, 1, 9 </pre> 11GR2: WITH t (cnt,people,pos,eliminated) AS ( SELECT MAX(ROWNUM) cnt,MAX(SYS_CONNECT_BY_PATH(LPAD(ROWNUM,4),',')),6,'' FROM DUAL CONNECT BY ROWNUM<=:input_num UNION ALL SELECT cnt-1,SUBSTR(people,1,pos-1)||SUBSTR(people,pos+5) ,CASE WHEN pos+5<LENGTH(SUBSTR(people,1,pos-1)||SUBSTR(people,pos+5)) THEN pos+5 WHEN pos+5<LENGTH(people) THEN 1 ELSE 6 END ,CAST(eliminated||SUBSTR(people,pos,5) AS VARCHAR2(200)) FROM t WHERE cnt>1 ) SELECT people,eliminated FROM t WHERE cnt=1; PEOPLE ------------------------------------------------------- ELIMINATED ------------------------------------------------------- , 5 , 2, 4, 6, 8, 10, 3, 7, 1, 9 ]]>