lower_bound

Interface

template<typename ForwardIterator, typename T>
inline SPROUT_CONSTEXPR ForwardIterator
lower_bound(ForwardIterator first, ForwardIterator last, T const& value);

template<typename ForwardIterator, typename T, typename Compare>
inline SPROUT_CONSTEXPR ForwardIterator
lower_bound(ForwardIterator first, ForwardIterator last, T const& value, Compare comp);

Requires

The elements e of [first,last) shall be partitioned with respect to the expression e < value or comp(e, value).

Returns

The furthermost iterator i in the range [first,last] such that for any iterator j in the range [first,i) the following corresponding conditions hold: *j < value or comp(*j, value).

Examples

#include <sprout/algorithm/lower_bound.hpp>
#include <sprout/array.hpp>
#include <sprout/container.hpp>
using namespace sprout;

SPROUT_STATIC_CONSTEXPR auto input = array<int, 10>{{1, 2, 3, 5, 5, 5, 5, 8, 9, 10}};
SPROUT_STATIC_CONSTEXPR auto result = sprout::lower_bound(begin(input), end(input), 5);
static_assert(result - begin(input) == 3, "a lower bound position is 3.");

Complexity

At most log2(last - first) + O(1) comparisons.

Recursive function invocations in O(logN) (logarithmic) depth.

Header

sprout/algorithm/lower_bound.hpp

Convenience header: sprout/algorithm.hpp