hamiltonian-cycle

Palmer's Algorithm for Hamiltonian cycles

时光总嘲笑我的痴心妄想 提交于 2019-12-04 13:31:10
In a "dense" graph, I am trying to construct a Hamiltonian cycle using Palmer's Algorithm . However, I need more explanation for this algorithm because it does not work with me when I implement it. It seems that there is an unclear part in Wikipedia's explanation. I would be thankful if someone explains it more clearly or give me some links to read. Here's the algorithm statement: Palmer (1997) describes the following simple algorithm for constructing a Hamiltonian cycle in a graph meeting Ore's condition. Arrange the vertices arbitrarily into a cycle, ignoring adjacencies in the graph. While

Algorithm to find a random Hamiltonian path in a grid?

放肆的年华 提交于 2019-12-04 12:02:52
问题 I'm looking for an efficient algorithm that is able to find an as random as possible Hamiltonian path in a bidirectional N*M grid. Does anyone know where I can find, or how to go about constructing such an algorithm? I've already found an efficient approach (see image below). The end result here is a Hamiltonian cycle. Removing a random edge will make it a Hamiltonian path. This algorithm is efficient, but does not provide enough randomness. This approach will always have the begin and end

Build all Hamiltonian paths from an edge list

流过昼夜 提交于 2019-11-30 15:55:40
I'm having trouble finding a way to build a tree path from a list of related tuples? I only want a list of every path where each node is visited once, aka hamiltonian path. I keep getting close but missing some path. For example, let's say we have this list of connections: connections = [(1, 4), (1, 5), (2, 5), (3, 4), (4, 1), (4, 3), (4, 5), (5, 1), (5, 2), (5, 4)] desired output: [[1,4,3], [1,4,5,2], [1,5,2], [1,5,4,3], [2,5,1,4,3], [2,5,4,1], [2,5,4,3], [3,4,1,5,2], [3,4,5,1], [3,4,5,2], [4, 3], [4,1,5,2], [4,5,1], [4,5,2], [5, 2], [5,1,4,3], [5,4,1], [5,4,3] ] So each possible path is

What is the dynamic programming algorithm for finding a Hamiltonian cycle in a graph?

不羁岁月 提交于 2019-11-30 10:39:52
问题 What is dynamic programming algorithm for finding a Hamiltonian cycle in an undirected graph? I have seen somewhere that there exists an algorithm with O(n.2^n) time complexity. 回答1: There is indeed an O(n2 n ) dynamic-programming algorithm for finding Hamiltonian cycles. The idea, which is a general one that can reduce many O(n!) backtracking approaches to O(n 2 2 n ) or O(n2 n ) (at the cost of using more memory), is to consider subproblems that are sets with specified "endpoints" . Here,

Algorithm for finding a Hamilton Path in a DAG

懵懂的女人 提交于 2019-11-29 22:52:03
I am referring to Skienna's Book on Algorithms. The problem of testing whether a graph G contains a Hamiltonian path is NP-hard , where a Hamiltonian path P is a path that visits each vertex exactly once. There does not have to be an edge in G from the ending vertex to the starting vertex of P , unlike in the Hamiltonian cycle problem. Given a directed acyclic graph G ( DAG ), give an O(n + m) time algorithm to test whether or not it contains a Hamiltonian path. My approach, I am planning to use DFS and Topological sorting . But I didn't know how to connect the two concepts in solving the

Build all Hamiltonian paths from an edge list

烂漫一生 提交于 2019-11-29 22:49:39
问题 I'm having trouble finding a way to build a tree path from a list of related tuples? I only want a list of every path where each node is visited once, aka hamiltonian path. I keep getting close but missing some path. For example, let's say we have this list of connections: connections = [(1, 4), (1, 5), (2, 5), (3, 4), (4, 1), (4, 3), (4, 5), (5, 1), (5, 2), (5, 4)] desired output: [[1,4,3], [1,4,5,2], [1,5,2], [1,5,4,3], [2,5,1,4,3], [2,5,4,1], [2,5,4,3], [3,4,1,5,2], [3,4,5,1], [3,4,5,2],

GCJ - Hamiltonian Cycles

淺唱寂寞╮ 提交于 2019-11-29 16:03:06
Code jam problem is the following: You are given a complete undirected graph with N nodes and K "forbidden" edges. N <= 300, K <= 15. Find the number of Hamiltonian cycles in the graph that do not use any of the K "forbidden" edges. Unfortunately the explanations of this here on stack and throughout the web are very insufficient. I can figure out HamCycles for a certain 'n' : (n-1)! / 2 . And I can do the short set with dynamic programming. But I don't get all the subset bologna, how to make it O^K? I'm in Python and have yet to decipher the C++ available. Eventually I'm sure I will take the

GCJ - Hamiltonian Cycles

◇◆丶佛笑我妖孽 提交于 2019-11-28 09:31:29
问题 Code jam problem is the following: You are given a complete undirected graph with N nodes and K "forbidden" edges. N <= 300, K <= 15. Find the number of Hamiltonian cycles in the graph that do not use any of the K "forbidden" edges. Unfortunately the explanations of this here on stack and throughout the web are very insufficient. I can figure out HamCycles for a certain 'n' : (n-1)! / 2 . And I can do the short set with dynamic programming. But I don't get all the subset bologna, how to make