lexicographical_compare

Interface

template<typename InputIterator1, typename InputIterator2>
inline SPROUT_CONSTEXPR bool
lexicographical_compare(
  InputIterator1 first1, InputIterator1 last1,
  InputIterator2 first2, InputIterator2 last2
  );

template<typename InputIterator1, typename InputIterator2, typename Compare>
inline SPROUT_CONSTEXPR bool
lexicographical_compare(
  InputIterator1 first1, InputIterator1 last1,
  InputIterator2 first2, InputIterator2 last2,
  Compare comp
  );

Returns

true if the sequence of elements defined by the range [first1,last1) is lexicographically less than the sequence of elements defined by the range [first2,last2) and false otherwise.

Remarks

If two sequences have the same number of elements and their corresponding elements are equivalent, then neither sequence is lexicographically less than the other.

If one sequence is a prefix of the other, then the shorter sequence is lexicographically less than the longer sequence.

Otherwise, the lexicographical comparison of the sequences yields the same result as the comparison of the first corresponding pair of elements that are not equivalent.

for (; first1 != last1 && first2 != last2; ++first1, ++first2) {
    if (*first1 < *first2) return true;
    if (*first2 < *first1) return false;
}
return first1 == last1 && first2 != last2;

An empty sequence is lexicographically less than any non-empty sequence, but not less than any empty sequence.

Examples

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

SPROUT_STATIC_CONSTEXPR auto input1 = array<int, 10>{{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}};
SPROUT_STATIC_CONSTEXPR auto input2 = array<int, 10>{{1, 2, 3, 4, 5, 6, 7, 11, 12, 13}};
SPROUT_STATIC_CONSTEXPR auto result = sprout::lexicographical_compare(begin(input1), end(input1), begin(input2), end(input2));
static_assert(result, "input1 < input2 by lexicographical comparison.");

Complexity

At most 2*min((last1 - first1), (last2 - first2)) applications of the corresponding comparison.

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

Header

sprout/algorithm/lexicographical_compare.hpp

Convenience header: sprout/algorithm.hpp