Give an integer N and the task is to print hollow half diamond pattern.

Examples:

Input : 6
Output :
# 
# # 
#   # 
#     # 
#       # 
#         # 
#       # 
#     # 
#   # 
# # 
# 

Input : 7
Output :
# 
# # 
#   # 
#     # 
#       # 
#         # 
#           # 
#         # 
#       # 
#     # 
#   # 
# # 
#  

Approach:

The idea is to break the pattern into two parts:

• Upper part:  For the upper half start the for loop with iterator (i) from 1 to n and one more for loop with iterator (j) from 1 to i.

# 
# # 
#   # 
#     # 
#       # 
#         # 
#           #  

• Lower part: For lower half start the for loop with iterator (n-1) to 1 and loop inside this for will remain same as for the upper half.

#         # 
#       # 
#     # 
#   # 
# # 
#

• Now we have to check this condition that if (i==j) or (j==1) then we have to print “#”, otherwise we have to print ” “(space).

Below is the implementation:

# python program to print
# hollow half diamond star


# function to print hollow
# half diamond star
def hollow_half_diamond(N):
	
	# this for loop is for
	# printing upper half
	for i in range( 1, N + 1):
		for j in range(1, i + 1):
			
			# this is the condition to
			# print "#" only on the
			# boundaries
			if i == j or j == 1:
				print("#", end =" ")
				
			# print " "(space) on the rest
			# of the area
			else:
				print(" ", end =" ")
		print()
	
	# this for loop is to print lower half
	for i in range(N - 1, 0, -1):
		
		for j in range(1, i + 1):
			
			if j == 1 or i == j:
				print("#", end =" ")
			
			else:
				print(" ", end =" ")
		
		print()

# Driver Code
if __name__ == "__main__":
	N = 7
	hollow_half_diamond( N )

Output:

# 
# # 
#   # 
#     # 
#       # 
#         # 
#           # 
#         # 
#       # 
#     # 
#   # 
# # 
#