Added Pascal Triangle

khalidmammadov · khalidmammadov · commit b28fc36c5a77 · 2020-01-07T21:34:32.000Z
diff --git a/pascal_triangle/pascal.py b/pascal_triangle/pascal.py
@@ -0,0 +1,73 @@
+"""
+    This module uses Python 3.8's a new feature
+    'math.comb'
+    to calculate Pascal Triangle (https://en.wikipedia.org/wiki/Pascal%27s_triangle)
+    and prints it into standard output
+    e.g.
+                     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
+
+"""
+
+import math
+import sys
+import logging
+
+
+def bin_expans(row, col):
+    """
+        Calculate binomial coefficient
+    """
+    nCr = math.comb(row, col)
+    return nCr
+
+
+def build_triangle(rows = 10):
+    """
+        Calculate triangle  
+    """
+    triangle = [[str(bin_expans(row, col))
+                    for col in range(row+1)] 
+                        for row in range(rows)]
+    return triangle
+
+
+def print_nicely(pascal_triangle):
+    """
+       Print a Pascal Triangle
+       iterable of iterables i.e. line and col
+    """
+    for _row in pascal_triangle:
+        str_row = " ".join(_row)
+        last_row_len = len(" ".join(pascal_triangle[len(pascal_triangle)-1]))
+        print(str_row.center(last_row_len, ' '))
+
+
+if __name__ == "__main__":
+
+    # Extract Python version info    
+    ver_major, ver_minor, _, _, _ = sys.version_info
+    
+    # Check if version is correct: should be above 3.8
+    if (ver_major*10 + ver_minor) < 38:
+        logger = logging.getLogger(__name__)
+        logging.warning("**** Python version must be above or equal to 3.8 for this module to work "
+                        "as it uses a new math's modules Combinatorial (math.comb) API ****")
+        exit()
+
+    # Check if a line argument is supplied and is valid
+    no_of_rows = sys.argv[1] if len(sys.argv) > 1 and sys.argv[1].isdigit() else 10
+
+    # Build and print
+    pascal_triangle = build_triangle(int(no_of_rows))
+    print_nicely(pascal_triangle)
+    
+
