Write and explain the Floyd Warshall algorithm to find the allpair shortest path
Question
Write and explain the Floyd Warshall algorithm to find the allpair shortest path
Solution
The Floyd Warshall algorithm is a dynamic programming algorithm used to find the shortest paths between all pairs of vertices in a graph. It works with both directed and undirected graphs, but it does not work with graphs that contain negative cycles. Here is a step-by-step explanation of the algorithm:
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Initialization: Create a 2D array of size VxV where V is the number of vertices in the graph. The element at the i-th row and j-th column of this array will represent the shortest distance from the i-th vertex to the j-th vertex. Initially, fill this array such that the diagonal elements (i.e., distances from a vertex to itself) are 0 and the off-diagonal elements are either the weight of the edge connecting the vertices (if an edge exists) or infinity (if there is no direct edge).
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Iteration: The main part of the algorithm involves three nested loops, each running V times. The outermost loop is for the intermediate vertices and the two inner loops are for the source and destination vertices. For each combination of source, destination, and intermediate vertices, check if the path from the source to the destination via the intermediate vertex is shorter than the current shortest path from the source to the destination (which may not involve the intermediate vertex). If it is, then update the shortest path.
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Result: After the iteration step, the 2D array will have been updated such that the element at the i-th row and j-th column represents the shortest distance from the i-th vertex to the j-th vertex, considering all possible intermediate vertices.
The time complexity of the Floyd Warshall algorithm is O(V^3) because of the three nested loops, each running V times. The space complexity is O(V^2) for the 2D array.
Similar Questions
Floyd-Warshall algorithm utilizes __________ to solve the all-pairs shortest paths problem on a directed graph in __________ time.
Floyd Warshall Algorithm used to solve the shortest path problem has a time complexity of __________
What approach is being followed in Floyd Warshall Algorithm?
Floyd Warshall Algorithm Given a graph in adjacency matrix from. Find shortest distances between every pair of vertices in a given edge weighted directed Graph. If there is no path from a source to a destination, print -1 at that place. Input Format: First line - n, the number of nodes Then there are n lines each containing n integers, weight from source(i.e. row number) to destination(i.e. column number). Output Format: Print shortest distances between every pair of vertices. If there is no path from a source to a destination, print -1 at that place. Sample Input: 4 0 5 INF 10 INF 0 3 INF INF INF 0 1 INF INF INF 0 Sample Output: 0 5 8 9 INF 0 3 4 INF INF 0 1 INF INF INF 0 give a pyhon code
The shortest path problem can be solved using:A. Depth-first searchB. Breadth-first searchC. Dijkstra's algorithmD. Floyd-Warshall algorithm
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