Learn how to print the pascal triangle patterns in javascript.

Example

" 1 " " 1 1 " " 1 2 1 " " 1 3 3 1 " " 1 4 6 4 1 "

Implementation

To print the pascal triangle in pyramid pattern, we will add white space to the left and the right and use a formula to generate the numbers.

We will use four loops to print the triangle in pyramid shape.

There will be a main loop which will be printing the each row and the three inner loops will generate the numbers.

First loop will add white space on the left, the second loop will generate the numbers with the formula number = number * (i - j) / (j + 1); and the third loop will add the white space on right.

let pascalTriangle = (rows) => { for(let i = 0; i < rows; i++){ let str = ''; let number = 1; //Add the white space to the left for(let k = 1; k <= (rows - i); k++){ str += ' '; } //Add the numbers sequence for each row for(let j = 0; j <= i; j++){ str += number + ' '; //Formula to calculate the pascal triangle number = number * (i - j) / (j + 1); } //Add the white space to the right for(let k = i + 1; k <= rows; k++){ str += ' '; } //Print the pattern for each row console.log(str); } }

Input: pascalTriangle(5); Output: " 1 " " 1 1 " " 1 2 1 " " 1 3 3 1 " " 1 4 6 4 1 "

Time complexity: O(n ^ 2).

Space complexity: O(1).

Time and Space complexity