set

问题 This question already has answers here : Is there possibility of sum of ArrayList without looping (13 answers) Closed 1 year ago . How would you find the sum of the elements of a set in Java? Would it be the same with an array? In python, I could do: my_set = {1, 2, 3, 4} print(sum(my_set)) 回答1: Aside from using loops explicitly, for List<Integer> list you can do: int sum = list.stream().mapToInt(Integer::intValue).sum(); If it's an int[] ar then do: int sum = IntStream.of(ar).sum(); This is

问题 Is there a simple way to verify that an ES6 Set contains a value that is a particular array? I'd like a solution that doesn't require me to use a reference: var set = new Set(); var array = [1, 2]; set.add(array); set.has(array); // true set.add([3, 4]); set.has([3, 4]); // false So far my solution is to store everything as a string, but this is annoying: set.add([3, 4].toString()); set.has([3, 4].toString()); // true 回答1: No there is not. A Set works on objects and primitives and is useful

问题 I'm trying to find a efficient algorithm to get all ways to partition a string eg for a given string 'abcd' => 'a' 'bcd' 'a' 'b' 'cd' 'a' 'b' 'c' 'd' 'ab' 'cd' 'ab' 'c' 'd' 'abc' 'd' 'a', 'bc', 'd any language would be appreciated Thanks in advance ! 回答1: Problem analysis Between each pair of adjacent characters, you can decide whether to cut. For a string of size n , there are n-1 positions where you can cut or not, i.e. there are two possibilities. Therefore there are 2^(n-1) partitions for

问题 I have a list of sets given by, sets1 = [{1},{2},{1}] When I find the unique elements in this list using numpy's unique , I get np.unique(sets1) Out[18]: array([{1}, {2}, {1}], dtype=object) As can be seen seen, the result is wrong as {1} is repeated in the output. When I change the order in the input by making similar elements adjacent, this doesn't happen. sets2 = [{1},{1},{2}] np.unique(sets2) Out[21]: array([{1}, {2}], dtype=object) Why does this occur? Or is there something wrong in the

问题 I have a list of sets given by, sets1 = [{1},{2},{1}] When I find the unique elements in this list using numpy's unique , I get np.unique(sets1) Out[18]: array([{1}, {2}, {1}], dtype=object) As can be seen seen, the result is wrong as {1} is repeated in the output. When I change the order in the input by making similar elements adjacent, this doesn't happen. sets2 = [{1},{1},{2}] np.unique(sets2) Out[21]: array([{1}, {2}], dtype=object) Why does this occur? Or is there something wrong in the

问题 I have a list of sets given by, sets1 = [{1},{2},{1}] When I find the unique elements in this list using numpy's unique , I get np.unique(sets1) Out[18]: array([{1}, {2}, {1}], dtype=object) As can be seen seen, the result is wrong as {1} is repeated in the output. When I change the order in the input by making similar elements adjacent, this doesn't happen. sets2 = [{1},{1},{2}] np.unique(sets2) Out[21]: array([{1}, {2}], dtype=object) Why does this occur? Or is there something wrong in the

问题 I have a list of sets given by, sets1 = [{1},{2},{1}] When I find the unique elements in this list using numpy's unique , I get np.unique(sets1) Out[18]: array([{1}, {2}, {1}], dtype=object) As can be seen seen, the result is wrong as {1} is repeated in the output. When I change the order in the input by making similar elements adjacent, this doesn't happen. sets2 = [{1},{1},{2}] np.unique(sets2) Out[21]: array([{1}, {2}], dtype=object) Why does this occur? Or is there something wrong in the

问题 I have a list of sets given by, sets1 = [{1},{2},{1}] When I find the unique elements in this list using numpy's unique , I get np.unique(sets1) Out[18]: array([{1}, {2}, {1}], dtype=object) As can be seen seen, the result is wrong as {1} is repeated in the output. When I change the order in the input by making similar elements adjacent, this doesn't happen. sets2 = [{1},{1},{2}] np.unique(sets2) Out[21]: array([{1}, {2}], dtype=object) Why does this occur? Or is there something wrong in the

问题 I couldn't figure out how to perform line.startswith("substring") for a set of substrings, so I tried a few variations on the code at bottom: since I have the luxury of known 4-character beginning substrings, but I'm pretty sure I've got the syntax wrong, since this doesn't reject any lines. (Context: my aim is to throw out header lines when reading in a file. Header lines start with a limited set of strings, but I can't just check for the substring anywhere, because a valid content line may

问题 I have a class that is compared only based on the content of its attributes, so that two objects with the same values are equivalent. class a(object): def __init__(self, value): self.value = value def __repr__(self): return 'a(value={})'.format(self.value) def __hash__(self): return hash(self.__repr__()) def __eq__(self, other): if not isinstance(other, self.__class__): return NotImplemented return self.value == other.value def __ne__(self, other): return not self.__eq__(other) When I create