The closest pair of points problem or closest pair problem is a problem of computational geometry: given n points in metric space, find a pair of points with the smallest distance between them. The closest pair problem for points in the Euclidean plane was among the first geometric problems which were treated at the origins of the systematic study of the computational complexity of geometric algorithms.
A naive algorithm of finding distances between all pairs of points and selecting the minimum requires O(dn2) time. It turns out that the problem may be solved in O(n log n) time in a Euclidean space or Lp space of fixed dimension d. In the algebraic decision tree model of computation, the O(n log n) algorithm is optimal. The optimality follows from the observation that the element uniqueness problem (with the lower bound of Ω(n log n) for time complexity) is reducible to the closest pair problem: checking whether the minimal distance is 0 after the solving of the closest pair problem answers the question whether there are two coinciding points.
In the computational model which assumes that the floor function is computable in constant time the problem can be solved in O(n log log n) time. If we allow randomization to be used together with the floor function, the problem can be solved in O(n) time.
Read more about Closest Pair Of Points Problem: Brute-force Algorithm, Planar Case, Dynamic Closest-pair Problem
Famous quotes containing the words closest, pair, points and/or problem:
“It is a fearful thing to lead this great peaceful people into war, into the most terrible and disastrous of all wars, civilization itself seeming to be in the balance. But the right is more precious than peace, and we shall fight for the things we have always carried closest to our hearts.”
—Woodrow Wilson (1856–1924)
“Oh, Jacques, we’re used to each other, we’re a pair of captive hawks caught in the same cage, and so we’ve grown used to each other. That’s what passes for love at this dim, shadowy end of the Camino Real.”
—Tennessee Williams (1914–1983)
“Wonderful “Force of Public Opinion!” We must act and walk in all points as it prescribes; follow the traffic it bids us, realise the sum of money, the degree of “influence” it expects of us, or we shall be lightly esteemed; certain mouthfuls of articulate wind will be blown at us, and this what mortal courage can front?”
—Thomas Carlyle (1795–1881)
“Will women find themselves in the same position they have always been? Or do we see liberation as solving the conditions of women in our society?... If we continue to shy away from this problem we will not be able to solve it after independence. But if we can say that our first priority is the emancipation of women, we will become free as members of an oppressed community.”
—Ruth Mompati (b. 1925)