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Sample Output:
>>> Enter the number of rows: 6
>>> Enter Symbol: *
***********
*********
*******
*****
***
*
Next, let us write a program to print an isosceles triangle using a given symbol (say, symbol). Program 6.14 shows
th
an isosceles triangle comprising six rows using asterisks. Note that the last row (6 row) does not have any leading
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spaces, 5 row has one leading space, the 4 row has two leading spaces, and so on. Finally, the first row has 5 (=6-1)
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th
spaces. Thus, i row has nRows-i leading spaces. Furthermore, the first row has one asterisk, the second row has
3 asterisks, and so on. Finally, the sixth row has 11 (=6×2-1) asterisks. Thus, i row has 2×i-1 asterisks. Now we are
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ready to write a program to display an isosceles triangle.
Program 6.14 To display the isosceles triangular pattern of a symbol
01 '''
02 Objective: To display an isosceles triangular pattern
03 Inputs:
04 nRows : number of rows
05 symbol: symbol to be printed
06 Output: Pattern of symbols
07 '''
08
09 nRows = int(input('Enter the number of rows: '))
10 symbol = input('Enter Symbol: ')
11
12 nSpaces = nRows-1
13 nSymbols = 1
14
15 for row in range(1, nRows + 1):
16 print(' ' * nSpaces, end = '')
17 print(symbol * nSymbols)
18 nSpaces = nSpaces - 1
19 nSymbols = nSymbols + 2
Sample Output:
>>> Enter the number of rows: 6
>>> Enter Symbol: *
*
***
*****
*******
*********
***********
6.7.3 Hollow Diamond
Now it is time to apply our learning to draw a hollow diamond pattern. Sample Output of the given program shows a
hollow diamond comprising 11 rows (six rows in a hollow upper isosceles triangle and five rows in an inverted hollow
isosceles triangle). To build a hollow upper isosceles triangle, nUpper is set to 6. In the first row, we need 5 (=6-1)
spaces followed by one asterisk. For the next row, we need 4 (=6-2) leading spaces. The leading spaces are followed
by two asterisks separated by one space, in all 3 (=2×2-1)characters. For the next row, we need 3(=6-3) leading spaces.
The leading spaces are followed by two asterisks separated by three spaces, in all and 5 (=2×3-1) characters. Thus,
146 Touchpad Informatics Practices-XI

