Keith KeithPiTsui
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| extension Array { | |
| var powerSet: [[Element]] { | |
| guard !isEmpty else { return [[]] } | |
| return Array(self[1...]).powerSet.flatMap { [$0, [self[0]] + $0] } | |
| } | |
| } | |
| print([1,2,3,4].powerSet) // -> [[], [1], [2], [1, 2], [3], [1, 3], [2, 3], [1, 2, 3], [4], [1, 4], [2, 4], [1, 2, 4], [3, 4], [1, 3, 4], [2, 3, 4], [1, 2, 3, 4]] |