How to build a pascal triangle

Question

i am trying to build a pascal triangle but output is not as expected i want output as

triangle = []

for i in range(num_rows):
row = [1] * (i + 1)
for j in range(1, i):
row[j] = triangle[i - 1][j - 1] + triangle[i - 1][j]
triangle.append(row)

return triangle

def print_pascals_triangle(triangle):
for row in triangle:
print(" ".join(map(str, row)))

try:
num_rows = int(input("Enter the number of rows for Pascal's Triangle: "))
if num_rows <= 0:
print("Please enter a positive integer.")
else:
pascals_triangle = generate_pascals_triangle(num_rows)
print_pascals_triangle(pascals_triangle)
except ValueError:
print("Invalid input. Please enter a valid integer.")

Answer 1

Calculation of the triangle is trivial. Output format can be performed with the aid of str.center() [ Thanks to @AKX for pointing that out ]

def pascal(n: int) -> list:
    r = []

    for i in range(1, n+1):
        row = [c := 1]
        for j in range(1, i):
            row.append(c := c * (i - j) // j)
        r.append(" ".join(map(str, row)))

    return r

if p := pascal(8):
    w = len(p[-1])
    for row in p:
        print(row.center(w))

Output:

         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