File : gss.sp


$ spar gss
 3
 5
 6
-2
-1
 4


#!/usr/local/bin/spar

pragma annotate( summary, "gss" )
       @( description, "greatest sequential sum" )
       @( description, "Given a sequence of integers, find a continuous subsequence which maximizes the" )
       @( description, "sum of its elements, that is, the elements of no other single subsequence add" )
       @( description, "up to a value larger than this one. An empty subsequence is considered to have" )
       @( description, "the sum 0; thus if all elements are negative, the result must be the empty" )
       @( description, "sequence." )
       @( see_also, "http://rosettacode.org/wiki/Greatest_subsequential_sum" )
       @( author, "Ken O. Burtch" );
pragma license( unrestricted );

pragma restriction( no_external_commands );

procedure gss is

  type int_array is array( 1..11 ) of integer;

  a : constant int_array := (-1 , -2 , 3 , 5 , 6 , -2 , -1 , 4 , -4 , 2 , -1);
  length : constant integer := arrays.length( a );

  beginmax : integer := 0;
  endmax : integer := -1;
  maxsum : integer := 0;
  sum : integer := 0;

begin

 for start in arrays.first(a)..length-1 loop
     sum := 0;
     for finish in start..length-1 loop
        sum := @ + a(finish);
        if sum > maxsum then
           maxsum := sum;
           beginmax := start;
           endmax := finish;
        end if;
     end loop;
  end loop;

  for i in beginmax..endmax loop
      ? a(i);
  end loop;

end gss;

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