27 lines
1.1 KiB
Python
27 lines
1.1 KiB
Python
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class Solution(object):
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# DFS: iterative implement.
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def is_additive_number(self, num):
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length = len(num)
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for i in range(1, int(length/2+1)):
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for j in range(1, int((length-i)/2 + 1)):
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first, second, others = num[:i], num[i:i+j], num[i+j:]
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if self.isValid(first, second, others):
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return True
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return False
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def isValid(self, first, second, others):
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if ((len(first) > 1 and first[0] == "0") or
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(len(second) > 1 and second[0] == "0")):
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return False
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sum_str = str(int(first) + int(second))
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if sum_str == others:
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return True
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elif others.startswith(sum_str):
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return self.isValid(second, sum_str, others[len(sum_str):])
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else:
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return False
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if __name__ == "__main__":
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print(Solution().is_additive_number('66121830'))
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print(Solution().is_additive_number('51123'))
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print(Solution().is_additive_number('235813'))
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