Python/dynamic_programming/sum_of_subset.py

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def is_sum_subset(arr, arr_len, required_sum):
"""
>>> is_sum_subset([2, 4, 6, 8], 4, 5)
False
>>> is_sum_subset([2, 4, 6, 8], 4, 14)
True
"""
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# a subset value says 1 if that subset sum can be formed else 0
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# initially no subsets can be formed hence False/0
subset = [[False for i in range(required_sum + 1)] for i in range(arr_len + 1)]
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# for each arr value, a sum of zero(0) can be formed by not taking any element
# hence True/1
for i in range(arr_len + 1):
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subset[i][0] = True
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# sum is not zero and set is empty then false
for i in range(1, required_sum + 1):
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subset[0][i] = False
for i in range(1, arr_len + 1):
for j in range(1, required_sum + 1):
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if arr[i - 1] > j:
subset[i][j] = subset[i - 1][j]
if arr[i - 1] <= j:
subset[i][j] = subset[i - 1][j] or subset[i - 1][j - arr[i - 1]]
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# uncomment to print the subset
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# for i in range(arrLen+1):
# print(subset[i])
print(subset[arr_len][required_sum])
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if __name__ == "__main__":
import doctest
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doctest.testmod()