Non-continuous subsequences: Difference between revisions

<lang cpp>

/*

* Nigel Galloway, July 19th., 2017 - Yes well is this any better?

*/

class N{

uint n,i,g,e,l;

public:

N(uint n): n(n-1),i{},g{},e(1),l(n-1){}

bool hasNext(){

g=(1<<n)+e;for(i=l;i<n;++i) g+=1<<i;

if (l==2) {l=--n; e=1; return true;}

if (e<((1<<(l-1))-1)) {++e; return true;}

e=1; --l; return (l>0);

}

uint next() {return g;}

};

</lang>

Which may be used as follows:

<lang cpp>

int main(){

N n(4);

while (n.hasNext()) std::cout << n.next() << "\t* " << std::bitset<4>(n.next()) << std::endl;

</lang>

{{out}}

<pre>

9 * 1001

10 * 1010

11 * 1011

13 * 1101

5 * 0101

</pre>