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For sparse graphs, that is, graphs with far fewer than | | edges, Dijkstra's algorithm can be implemented more efficiently by storing the graph in the form of adjacency lists and using a self-balancing binary search tree, binary heap, pairing heap, Fibonacci heap or a priority heap as a priority queue to implement extracting minimum efficiently.
The amortized performance of a Fibonacci heap depends on the degree (number of children) of any tree root being (), where is the size of the heap. Here we show that the size of the (sub)tree rooted at any node x {\displaystyle x} of degree d {\displaystyle d} in the heap must have size at least F d + 2 {\displaystyle F_{d+2}} , where F i ...
Chen et al. [11] examined priority queues specifically for use with Dijkstra's algorithm and concluded that in normal cases using a d-ary heap without decrease-key (instead duplicating nodes on the heap and ignoring redundant instances) resulted in better performance, despite the inferior theoretical performance guarantees.
For graphs of even greater density (having at least |V| c edges for some c > 1), Prim's algorithm can be made to run in linear time even more simply, by using a d-ary heap in place of a Fibonacci heap. [10] [11] Demonstration of proof. In this case, the graph Y 1 = Y − f + e is already equal to Y. In general, the process may need to be repeated.
From a dynamic programming point of view, Dijkstra's algorithm for the shortest path problem is a successive approximation scheme that solves the dynamic programming functional equation for the shortest path problem by the Reaching method. [8] [9] [10] In fact, Dijkstra's explanation of the logic behind the algorithm, [11] namely Problem 2.
The first three stages of Johnson's algorithm are depicted in the illustration below. The graph on the left of the illustration has two negative edges, but no negative cycles. The center graph shows the new vertex q, a shortest path tree as computed by the Bellman–Ford algorithm with q as starting vertex, and the values h(v) computed at each other node as the length of the shortest path from ...
If the Bellman–Ford algorithm is used for this step, the running time of the Hungarian algorithm becomes (), or the edge cost can be shifted with a potential to achieve ( +) running time with the Dijkstra algorithm and Fibonacci heap. [7]
Use a shortest path algorithm (e.g., Dijkstra's algorithm, Bellman-Ford algorithm) to find the shortest path from the source node to the sink node in the residual graph. Augment the Flow: Find the minimum capacity along the shortest path. Increase the flow on the edges of the shortest path by this minimum capacity.