48 lines
852 B
Python
48 lines
852 B
Python
# A dynamic programming based function to find nth
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# Catalan number
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"""
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Output:
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The first 10 terms of Catalan sequence are :
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1 1 2 5 14 42 132 429 1430 4862
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"""
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def catalan(n):
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"""
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>>> catalan(2)
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2
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>>> catalan(5)
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42
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>>> catalan(-1)
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Traceback (most recent call last):
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...
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IndexError: list assignment index out of range
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"""
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# Base Case
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if n == 0 or n == 1:
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return 1
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# To store the result of subproblems
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cat_num = [0] * (n + 1)
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cat_num[0] = 1
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cat_num[1] = 1
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for i in range(2, n + 1):
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for j in range(i):
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cat_num[i] += cat_num[j] * cat_num[i - j - 1]
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return cat_num[n]
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n = 10
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if n<0:
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print("Please add a valid number")
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exit()
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print(f"The first {n} terms of Catalan sequence are : ")
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for i in range(n):
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print(catalan(i), end=" ")
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