I want to write 开发者_运维知识库a program that gets an integer n and prints all the permutations of 1,2,...,n. I know there is a recursive way to do this and I know the overhead of function calls. Is there any way to do this without recursion??
Yes, you can do it iteratively with std::next_permutation
from <algorithm>
as a while
condition, or depending on how you set up the loop this may be one of the occasions where do...while
is more appropriate.
#include <vector>
#include <algorithm>
std::vector<int> v = { 1,2,3,4,5,6,7,8,9,10 }; // see std::iota also
// important: sort v if not sorted
std::sort(v.begin(), v.end());
while (std::next_permutation(v.begin(), v.end()))
{
// use v (unique permutation)
}
// use v: first sorted position
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