背包算法+接近过程

求最接近的解：
declare
   type test_t is table of vw_money%rowtype index by binary_integer;
   res test_t;
   l_row binary_integer:=1;
   sums number;
   cal varchar2(1000);
   seq varchar2(1000);
   j NUMBER;
   lv_result NUMBER;
   lv_target NUMBER := 33;
   lv_cal VARCHAR2(1000);
   lv_seq VARCHAR2(1000);
begin

  SELECT *
  BULK COLLECT INTO res
  FROM vw_money;
 
  --dbms_output.put_line(res.count);
  lv_result := NULL;
  for i in res.first .. 2**res.last-1 loop
      sums:=0;
      seq:='';
      cal:='';
      j:=1;
      WHILE j<=res.count AND res(j).pow<=i LOOP
       if (bitand(i,res(j).pow) <> 0) then  -- 2的幂事先算好了
         sums:=sums+res(j).amount;
         cal:=cal||res(j).amount||'+';
         seq:=seq||res(j).id||',';  
         IF sums - lv_target >= ABS(lv_result - lv_target) THEN        ---- 已经有更接近的答案
            EXIT;
         END IF;
       end if;
       j:=j+1;
      end loop;
      IF lv_result IS NULL OR ABS(sums - lv_target) < ABS(lv_result - lv_target) THEN
         lv_result := sums;
         lv_cal := cal;
         lv_seq := seq;
      END IF;
      IF lv_result = lv_target THEN
         EXIT;
      END IF;
  end loop;
 
  lv_cal:=substr(lv_cal,1,length(lv_cal)-1);
  lv_seq:=substr(lv_seq,1,length(lv_seq)-1);
  dbms_output.put_line('结果是:'||lv_cal||'='||lv_result);
  dbms_output.put_line('序列是:'||lv_seq);

end;