PROGRAM 2


--  Filename:  program2.adb      Author:  Anthony F. Ortiz    
--  This program finds and displays the integer n between 2 and 500 that 
--  generates the longest hailstone sequence.   

with Text_IO;   use Text_IO;

procedure Hailstones is
    package Int_IO is new Integer_IO (Integer);     use Int_IO;
    Hailstone :  Integer;         -- Stores current hailstone.
    Count_N : Integer := 2;       -- Starting sequence for hailstone.
                                  -- Initialize to 2.
    Count_Terms : Integer := 1;   -- Count # of terms in current hailstone.
                                  -- Initialize to 1.
    Max_Hailstone : Integer := 0; -- Maximum hailstone sequence.
                                  -- Initialize to 0.  
    Max_Terms : Integer := 0;     -- Maximum # of terms in this sequence.
                                  -- Initialize to 0.
begin
    -- Stop loop when the starting sequence is greater than 500.
    while (Count_N <= 500) loop
        -- Set next starting hailstone.
        Hailstone := Count_N;
        -- Stop loop when hailstone = 1.
        while (Hailstone /= 1) loop
            -- If hailstone is even, use formula 1 to get next 
            -- hailstone.
            -- If hailstone is odd, use formula 2 to get next
            -- hailstone.
            if (Hailstone mod 2 = 0) then
                Hailstone := Hailstone / 2;   
            else
                Hailstone := Hailstone * 3 + 1;
            end if;
            -- Count number of terms in current hailstone sequence.
            Count_Terms := Count_Terms + 1; 
        end loop;
        -- If current number of terms is greater than the 
        -- maximum number of terms, the greatest hailstone =
        -- the current starting sequence of hailstone and the
        -- maximum number of terms is equal to the current 
        -- number of terms.
        if (Count_Terms > Max_Terms) then
            Max_Hailstone := Count_N;
            Max_Terms := Count_Terms;
        end if;
        -- Compute number of next starting sequence and 
        -- set number of terms equal to 1.
        Count_N := Count_N + 1;
        Count_Terms := 1;
    end loop;
    -- Display greatest hailstone sequence and it's # of terms.
    Put ("the greatest hailstone sequence is ");
    Put (Max_Hailstone);
    New_Line;
    Put ("the number of terms is ");
    Put (Max_Terms);
end Hailstones;

--  outfile:  program2.out

the greatest hailstone sequence is         327
the number of terms is         144




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