pascals-triangle

A function to return n lines of Pascal's Triangle.

Usage

pascalsTriangle(numberOfRows): Return n lines of Pascal's Triangle as a multi-dimensional array.

let triangle = pascalsTriangle(5);
console.log(triangle);

[ [ 1 ],
  [ 1, 1 ],
  [ 1, 2, 1 ],
  [ 1, 3, 3, 1 ],
  [ 1, 4, 6, 4, 1 ],
  [ 1, 5, 10, 10, 5, 1 ] ]

printRightTriangle(triangle, numberOfSpaces, paddingCharacter): Format array as a right triangle with equally spaced columns.

let triangle = pascalsTriangle(10);
let str = printRightTriangle(triangle, 2, ' ');
console.log(str);

1
1    1
1    2    1
1    3    3    1
1    4    6    4    1
1    5    10   10   5    1
1    6    15   20   15   6    1
1    7    21   35   35   21   7    1
1    8    28   56   70   56   28   8    1
1    9    36   84   126  126  84   36   9    1
1    10   45   120  210  252  210  120  45   10   1

nChooseK(n,k): return the value from any place in Pascal's Triangle using combinations: n choose k( n = row, k = term ).

// log all values k for row 5
console.log(nChooseK(5,0));
1

console.log(nChooseK(5,1));
5

console.log(nChooseK(5,2));
10

console.log(nChooseK(5,3));
10

console.log(nChooseK(5,4));
5

console.log(nChooseK(5,5));
1

format(triangle, preRow, postRow, preColumn, postColumn): wraps individual elements and rows with provided values.

For example, to create an HTML table:

let triangle = pascalsTriangle(15);
// make all rows the same length, so they have the same number of columns
let nTriangle = normalizeRows(triangle,'');
let html = [];
html.push('<table>');
html.push('<tbody>');
html.push(format(nTriangle, '<tr>', '</tr>', '<td>', '</td>'));
html.push('</tbody>');
html.push('</table>');
console.log(html.join('\n'));

1
1	1
1	2	1
1	3	3	1
1	4	6	4	1
1	5	10	10	5	1
1	6	15	20	15	6	1
1	7	21	35	35	21	7	1
1	8	28	56	70	56	28	8	1
1	9	36	84	126	126	84	36	9	1
1	10	45	120	210	252	210	120	45	10	1
1	11	55	165	330	462	462	330	165	55	11	1
1	12	66	220	495	792	924	792	495	220	66	12	1
1	13	78	286	715	1287	1716	1716	1287	715	286	78	13	1
1	14	91	364	1001	2002	3003	3432	3003	2002	1001	364	91	14	1
1	15	105	455	1365	3003	5005	6435	6435	5005	3003	1365	455	105	15	1