breadth-first-search

问题 I need some clarifications and inputts regarding Dijktra's algorithm vs breath first search in directed graphs, if these are correct. Dijktra's algorithm finds the shortest path from Node A to Node F in a weighted graph regardless of if there is a cycle or not (as long as there are no negative weights) but for that, All paths from A to all other Nodes in the graph are calculated and we grab the path from A to F by reversing the sequences of nodes in prev`. BFS: finds the shortest path from

问题 graph={ 0:[1,3,4], 1:[0,2,4], 2:[1,6], 3:[0,4,6], 4:[0,1,3,5], 5:[4], 6:[2,3] } def bfs(graph, start, path=[]): queue = [start] while queue: vertex = queue.pop(0) if vertex not in path: path.append(vertex) queue.extend(graph[vertex] - path) return path print bfs(graph, 0) Guys! Can someone help me with this bfs code? I can't understand how to solve this queue line. 回答1: To extend your queue with all nodes not yet seen on the path, use set operations: queue.extend(set(graph[vertex]).difference

问题 How many paths possible in android pattern lock? I thought it can be calculated simply by factorial, with formula (9!)/(9-length)! Examples: For length 9, there are 9*8*7*6*5*4*3*2*1 paths. For length 8, there are 9*8*7*6*5*4*3*2 paths. For length 7, there are 9*8*7*6*5*4*3 paths. etc. Here is the code for calculating this: def paths_of_length(number_of_staring_points, length_of_path): print("number_of_staring_points", number_of_staring_points, "length_of_path", length_of_path) different

问题 The no. of nodes generated by breadth-first search is, according to my book: N(BFS) = b + b^2 + .... + b^d + ( b^(d+1) - b ) where b is the branching factor and d is the depth of the shallowest node. But should't it just be b + b^2 + .... + b^d ? because that, according to me is the no. of nodes till the depth of the goal. So why's there the + ( b^(d+1) - b ) ? 回答1: There is a difference in a number of generated nodes by breadth first search depending on the variant of the algorithm you use.

问题 I have a two dimensional matrix like A......... ##....##.. .####...## .......... .......### B......... ####...### #...#.###. Where ' . ' represents path and ' # ' represents wall.I have to find the shortest path possible from point A to point B .I am familiar with BFS algorithm and it seems like a reasonable algorithm for the problem. But I find it confusing to apply on the grid.Can anyone suggest implementation of BFS algorithm in this problem with some pseudo-codes ? 回答1: The BFS algorithms

问题 http://pastebin.com/dN9a9xfs That's my code to print out the elements of a binary search tree. The goal is to display it in level order, with slashes connecting the parent to each child. So for instance, the sequence 15 3 16 2 1 4 19 17 28 31 12 14 11 0 would display after execution as: 15 / \ 3 16 / \ \ 2 4 19 / \ / \ 1 12 17 28 / / \ \ 0 11 14 31 I've been working on it for a long time now, but I just can't seem to get the spacing/indentation right. I know I wrote the proper algorithm for

问题 I am trying to use adjacency list to compute the distance from a source vertex to the other vertices. I am using a queue to accomplish this however I get the distance of each vertex besides the source as -1, but I am not sure why this is happening #include <stdio.h> #include <stdlib.h> #include "input_error.h" #define VertexToSearch 1 typedef struct edge { int vertexIndex; struct edge *edgePtr; } edge; typedef struct vertex { int vertexKey; struct edge *edgePtr; int visited; int distance; }

问题 I have to analyze an m-ary tree in C - using namely BFS. There are some requirements I don't succeed to implement for a while: 1. Find the diameter of the tree. 2. Given two vertices in the tree - find the shortest simple path between them. As for 1 - I went through the topics in Stack - and have seen some implementations (not in C unfortunately) which are not very clear to me... Some way of calculating the diameter by using BFS twice, starting from a random vertex... I'm not sure if the

问题 I am having problem to print out all the possible paths. Currently I am only able to print out one path, and if (path-demo "J" "I"), the program will shown this error mcdr: expects argument of type <mutable-pair> ; given #f (define net '(("A" "B") ("B" "A" "C") ("C" "B" "D") ("D" "C" "E" "F") ("F" "I" "D") ("I" "F") ("E" "D" "J") ("J" "E" "G") ("G" "J" "H"))) (define (path-demo start finish) (for-each (lambda (x) (display x) (display " ")) (cons "Route:" (shortest-path start finish net))))

问题 I was trying out an iterative method to find the height/depth of a binary search tree. Basically, I tried using Breadth First Search to calculate the depth, by using a Queue to store the tree nodes and using just an integer to hold the current depth of the tree. Each node in the tree is queued, and it is checked for child nodes. If child nodes are present, then the depth variable is incremented. Here is the code: public void calcDepthIterative() { Queue<TreeNode> nodeQ = new LinkedList