Pascal's triangle: Difference between revisions

=={{header|BASIC}}==

===Summing from Previous Rows===

{{works with|FreeBASIC}}

This implementation uses an array to store one row of the triangle.

DIM initializes the array values to zero. For first row, "1" is then stored in the array.

To calculate values for next row, the value in cell (i-1) is added to each cell (i).

This summing is done from right to left so that it can be done on-place, without using a tmp buffer.

Because of symmetry, the values can be displayed from left to right.

Space for max 5 digit numbers is reserved when formatting the display.

The maximum size of triangle is 100 rows, but in practice it is limited by screen space.

If the user enters value less than 1, the first row is still always displayed.

<freebasic>DIM i AS Integer

DIM row AS Integer

DIM nrows AS Integer

DIM values(100) AS Integer

INPUT "Number of rows: "; nrows

values(1) = 1

PRINT TAB((nrows)*3);" 1"

FOR row = 2 TO nrows

PRINT TAB((nrows-row)*3+1);

FOR i = row TO 1 STEP -1

values(i) = values(i) + values(i-1)

PRINT USING "##### "; values(i);

NEXT i

PRINT

NEXT row</freebasic>

===Using binary coefficients===

{{works with|FreeBASIC}}

This implementation does not need an array to store values for each row, but the calculation is slightly more complex.

If the user enters value less than 1, nothing is displayed.

<freebasic>DIM c AS Integer

DIM i AS Integer

DIM row AS Integer

DIM nrows AS Integer

INPUT "Number of rows: "; nrows

FOR row = 0 TO nrows-1

c = 1

PRINT TAB((nrows-row)*3);

FOR i = 0 TO row

PRINT USING "##### "; c;

c = c * (row - i) / (i+1)

NEXT i

PRINT

NEXT row</freebasic>